This sounds like a ISP issue more than anything else, i would try contacting them

I have also tried repairing the connection in Network Connections in control panel & comes up with repair connection failed the renewing of IP address.

What happens when you restart the pc? Do you get a connection then? Do you have another system you can try it out on? I'm assuming that you're running Windows XP, right? What does the ipconfig /all command give you? What do the lights on the cable modem indicate?

There are plenty of things that could be going on with the system. Possibly, it's an ISP issue. Considering the way my ISP is, I like to eliminate everything on my side before calling them up.

When i restart the PC it works fine but crashes again after a while, the lights just flash continuously, but cant access the net or anything that connects to the net like msn. I dont think it is an ISP issue coz i reformated my HD & worked fine UNTIL i used TCP Optimizer
http://www.speedguide.net/faq_in.php?category=100
Ive eliminated all possibilities like hacking, virus,ISP etc, the TCP Optimizer worked fine when i used it before, but just recently i updated my Cable modem drivers & applied the Optimizer & now its causing problems, so im suspecting the Optimizer, what do u think???

What happens when you don't run mIRC?

I first notcied the crash while i was using Mirc constantly, but now even when i dont use it, it still crashes.

I went back to the windows default settings on TCP optimizer, & it still crashes, so its not the optimizer thats causing the problem. Other guess's are that theres some fault in the box or USB.

Problem sorted! just installed windows service pack 1 & seems to have wiped out the problem. No crashes since installing it

The problem seems to have come back again, the cable modem crashed & this time when i go to re-boot it comes up with a blue screen saying some sort of error in ntfs.sys, i dont know if that had caused the crash this time round, should i re-install XP?