The ABS cuts in intermittently at low speed on my 3.0l x type, there are no warning lights on the slip rings appear to be ok any suggestions would be welcome.

You need a mechanic with a high level scan tool to check the Diagnostic Trouble Codes and Live Data. It is probably ABS Sensor related, but should never leave you with no brakes..

Abs reluctor ring faulty

have you checked abs rings on drive shafts if broke abs will pump as its thinking its wheel is slipping you could wire brush them to see if they are broke

bit of dirt in abs ring
jet wash all wheels to clear the dirt

Check your brake fluid level first. If it is fine then you probably have a bad abs brake sensor.

ABS/ASC module is faulty
CLASSIC ABS FAILURE SYMPTOMS:
- Most of the time, the problem is the ABS module or one of the 4 wheel speed sensors (& sometimes the brake pressure sensor)
- In my 2002 BMW E39 DSC, three orange (warning) cluster display lights lit, ABS, Brake, & DSC
- The 3 warning lights reset when the ignition is turned off, only to repeatedly reappear within minutes of normal driving
- The fault is often intermittent leading you to falsely believe you've resolved the problem (proper diagnosis is important)
- Sometimes the fault only appears when the engine is hot; other times only at speeds over 40 mph
- Carsoft may erroneously show a rear speed sensor failure; but just replacing the speed sensor may make no difference.
- All the work is in correct diagnosis of the problem; parts replacement is trivial (from 1 to six bolts in a few minutes)
- Hence, this BMW E39 ABS 3-warning light DIY will concentrate on understanding and diagnosis of the problem

Bad ABS control module. This guy rebuilds them: http://home.earthlink.net/~vicrocha/Volvo_Parts/Volvo_ABS_removal.htm

Anti-Lock Control —Vehicles Built After 03/2002 The 3-channel anti-lock brake system consists of the following components:

• front wheel speed sensors
• front wheel speed sensor rings
• hydraulic control unit (HCU)
• Anti-lock brake control module (ECU)
• rear wheel speed sensor
• rear wheel speed sensor rings
• yellow anti-lock brake warning indicator

The 4-channel anti-lock brake system with traction control and stability assist system consists of the following components:

• active brake booster with integral solenoid
• brake booster release switch
• front wheel speed sensors
• front wheel speed sensor rings
• hydraulic control unit (HCU)
• stability assist module (ECU)
• stability assist event indicator
• lateral accelerometer
• longitudinal accelerometer (4x4)
• rear wheel speed sensors
• rear wheel speed sensor rings
• steering wheel position sensor
• yaw rate sensor
• yellow anti-lock brake warning indicator
• brake pressure transducer
• traction control switch

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I suspect the abs issue is causing the speed control not to work if it happened at the same time the cruise control stopped working. When the yellow ABS light comes on, it means the ABS is dactivated. You may have a faulty accelerometer which senses acceleration and yaw (side to side lean). I have not seen a bad one but you said it is sensitive to acceleration.
I would unplug it and see what happens. The connector should have a small tab to depress so you can pull the connector out.
Here is where it is:

Accelerometer Removal and Installation

1. NOTE: The accelerometer is located under the center, rear passenger seat carpet. (I think you have to remove seat for access).
   Cut the carpeting along the perforations.

1. Disconnect the electrical connector.

1. Remove the nuts and remove the accelerometer.

Have dealer hook up tester and pull fault codes if you can't find an easy solution.
Some background info

A malfunction in the anti-lock brake system will cause the anti-lock brake control module to shut off or inhibit the system. However, normal power-assisted braking remains.

Malfunctions are indicated by the yellow ABS warning indicator in the instrument cluster.

The anti-lock brake system is self-monitoring. When the ignition switch is turned to the RUN position, the anti-lock brake control module will carry out a preliminary self-check on the anti-lock electrical system indicated by a three-second illumination of the yellow ABS warning indicator in the instrument cluster.

During vehicle operation, including normal and anti-lock braking, the anti-lock brake control module monitors all electrical anti-lock functions and some hydraulic operations.

Each time the vehicle is driven, as soon as vehicle speed reaches approximately 20 km/h (12mph), the anti-lock brake control module turns on the pump motor for approximately one-half second. At this time, a mechanical noise may be heard. This is a normal function of the self-check by the anti-lock brake control module.

Pedal pulsation coupled with noise while braking on loose gravel, bumps, wet or snowy roads is normal and indicates correct functioning of the anti-lock brake system.

Warning Lamp Indicator
The anti-lock brake system (ABS) uses the yellow ABS warning indicator to alert the driver of a malfunctions in the ABS.
The yellow ABS warning indicator will come on to warn the driver that the ABS has been turned off due to a symptom that exists in the ABS. Normal power assist braking remains but wheels can lock during a panic stop while the yellow ABS warning indicator is illuminated.

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Please report back, I am curious if that is what it is. Good luck

Sounds as if you have a false activation of the ABS system.
If the light does not come on until you are driving then the ABS module is probably seeing a difference in wheel speed from side to side. It could be caused by different size tires,are all your tires the same size and brand? It could be caused by one tire having low tire pressure. It could also be one of the sensor rings esp. on the front has maybe cracked and slipped out of place causing the air gap between the sensor and the ring to be larger than it is suppose to be.The gap between sensor and ring is usually 0.045 of an inch sometimes the ring which is pressed onto the outer CV joint will crack and the ring will slid up the joint slightly away from the sensor.This will decrease the amplitude of the sensor signal and ABS interputs this as a wheel trying to slip or lock up and activates the ABS.When ABS activates it will make a loud pulsing type sound and it will almost feel like it is not going to stop.

Ok, check the brake fluid level for a start. This could mean a few things. Your brake pads might be worn down, which would bring a yellow warning light on(triangle), at the same time with the pads being low it will have displaced the fluid, making the level low, this would be a red light on. Now because of this the body control module has detected these faults, will have turned the abs off, hence the abs light.
If brake fluid is low, this could confirm my theory.
If its low, top up with dot 5 brake fluid and take to garage to have new pads fitted.

TL