UNABLE TO CONNECT WITH MY LAP TOP ON INTERNET HAVE FOUR LIGHTS ON AND FIFTH ONE FLASHING JUST STARTED YESTERDAY.

So that means its working well and connected to the ISP' server. What is your connection? Is it ADSL?
First make sure that all light have the color of green. If they are Flashing with color RED that means the property associated with the light is having a failure.
Here are the description of Colors and Lights.
Modem Light state: Unlit Flashing Red Flashing Green Steady Green
Cases:::
Power Light
Modem is not getting power - no light Modem has failed POST - Red Power is on - Steady Green
Ethernet (2nd Light)
No Ethernet link detected - No light Problem with ethernet port or cable - Flashing Green Modem has detected a successful link to a PC or router - Steady Green
DSL (3rd light)
ADSL sync signal is not detected - Red Modem is trying to synchronize. - Flashing Green Modem has ADSL sync and is ready for PPPoE session traffic - Steady Green.
Internet (4th light)
Modem has given up or isn't configured to initiate the PPPoE session - No Light PPPoE initiation has failed or PPPoE has been terminated. - Red Initiating a PPPoE session to Internet - Flashing Green. Modem is ready for Internet traffic - Steady Green.
Note: This light sometimes not working even if the connection initiated.
Activity
Normal DSL traffic flow - Flashing Green. Steady traffic flow - Steady Green.
Solving problems.
Case1: You have to connect your machine to the Modem Via the Network cable. Plug the other side of the cable to your Machine. (Not the modem port. Network card port.). Case2: You have to make sure that you have installed the Network Card drives. To check that you have to use Device Manager. Follow these steps. Hit Windows key with R In the "Run" box type devmgmt.msc In the right hand side check whether the network card is installed. If it has a yellow exclamation mark or a mark with red that means you haven't either installed or its having a device/driver problem.
Case3: If its fine then what you have to do is to check your network settings. Heres how: Since you haven't specified the Operating System I m including the Windows XP method here. Not much difference in other Operating Systems as well.

• Get the Control Panel.
• Go to Network and Internet Connections.
• Go to Network Connections.
• Check the Local Area Connection.
• Right Click and check "Status".
• If it says connected
• Check the Duration and Speed(100 or 1000Mbps).
• If the settings are fine go to "Support" Tab.
• Check whether the Machine has received an IP Address. Which is often in the range of 192.168.254.xxx for Siemens Modems/Routers.
• If you see an IP Address which starts from 169.xxx.xxx.xxx your network card was unable to pick an IP Address from the DHCP router which runs in the modem. (If you run a DHCP in the machine you have to configure to stop leasing IP Addresses to your machine from the Router/Modem. You can try the "Repair" button below and it will try to Release and Renew your IP. If it fail either you have a problem with your network card or Modem/Router (Could be the cable also).
• If you still see the IP Address which starts with 192.168 the connection with your Modem is fine.
• Next: Right Click on the Local Area Connection again.
• Go to "Properties".
• Double Click on "Internet Protocol (TCP/IP).
• Check the settings.
• The settings should be "Obtain IP Addresses Automatically" and "Obtain DNS Server Address Automatically". (But if you know the router's/Modem's IP Address you can configure it and you can give a "Static IP" to your PC as well. It must not be the Router's / Modem's IP and must be in th SAME SUBNET. If router uses 192.168.254.xxx you can assign it as 192.168.254.2)
• Then Apply the Settings and go to the "Status" again and then click on "Details".
• Except Wins Server all others must be populated with values in 192.168 range. Check the "Default Gateway" Setting. Its very important that you have pointed the machines Default Gateway to the Router/Modem.
• Final Check:
• Go to the "Internet Protocol (TCP/IP) again and click on "Advanced".
• Check IP Settings (first tab) too make sure DHCP is enabled on you machine.
• Go to "Options" tab and Check TCP/IP Filtering. Click on properties and make sure that the Filtering is not enabled. If it enabled make sure your network adapter Permits all routers traffic in to the machine.

By following these options will let you surf the internet.
Check for the behaviors of indicators as well.
Case 3 :Browser settings
In the Internet Explorer go to: Tools -> Internet Options ->Connections -> LAN Settings -> Its fine if any box is not checked. Or you can check the "Automatic Detection".
Last thing is If you have a Firewall or Antivirus Suite Please make sure that you are not blocking adapters and traffic/application. You can try to disable Windows Firewall and check whether it works as well.
Hope this will solve your issue. Please be kind enough to rate the answer with a comment (testimonial) if this helps you to overcome the issue. Feel free to contact us further. Thanks for contacting Fixya