My dell inspiron 1720 locks up frequently - this problem started just yesterday I've used CC Cleaner and tried to do a complete virus scan using Kaspersky software - computer locked up at 7% into the scan.

In first place you still have the dell warranty because you have use the notebook for only 6 month, but the explanation that states indicates that your machine has a virus, I suggest to take the machine to a rapair shop. Good luck

u have a virus, spam download anti virus , or anti spam killer,scan ur pc with it and then download reginout to clean ur registry errors and viruses

If MalwareBytes Anti-Malware tool and Avast anti-virus boot scan do not rid your system of the virus, you may have to remove the hard drive from the infected computer and using an adapter, attach it to another computer such as a laptop or another desktop. The adapter attaches to the hard drive and then uses a usb for the interface. They can be bought at computer stores for around 20 bucks. Once you have attached the infected drive, double click on the "My Computer" icon and then right click on the infected drive icon. Scroll down until you see the selection for either "scan with MalwareBytes" or "Scan with Avast". ONce these scans are complete, replace the hard drive back into the original system. Another great scanner is Super AntiSpyware. All these are free downloads at www.filehippo.com

This must be the work of a virus... Please update your antivirus,, and do a complete system scan...
You can also repair your registry files using Registry Mechanic, CleanMyPC registry cleaner etc...

Download here:
http://en.kioskea.net/telecharger/telecharger 1953 registry mechanic
http://www.registry-cleaner.net/

It's probably a win32pirate.b.worm virus, but try the registry cleaner as well

Get it re formatted completely and doing a new partition.

First try holding down the insert key while booting. Next either your F1 or F2 key will get you into bios.
Try pressing those keys alternately while booting to enter setup. If you get to bios follow the previous poster's advice.
Try re seating the ram boards and the hard drive. Make sure you don't have any usb flash drives installed.

Maybe your antivirus couldn't detect viruses which infects your pc. Try to download this link: http://download.cnet.com/3001-2239_4-10683930.html?spi=965db5d6da80e31e89f9739f7725d860&part=dl-10683930. This is one of the most powerful antivirus nowadays.

Try the FN (function key) and the Nmlk (number lock Key) at the same time.

it may come from viruses that attacked your comptr..in start up, pressing F8 to run safe mode n try to scan your compter using good anti virus software

there are several reasons why a pc restarts: 1. there might be a virus that causes this, thry to scan your computer using the updated anti virus. 2. your power supply might be faulty, if your pc frequently restarts the 12volts supply is having a problem, you need to replace the power supply. 3. operating system error, you need to repair your OS. what i have suspected from the problem you relayed is that your power supply, you need to replace this.