When I'm driving or watching someone else driving in LFS my computer freezes totally, all I can do is restarting computer by pushing power button.
My computer is already 5 years old but it should run LFS still easily. I'm also using Windows XP Home Edition. Before it freezes game isin't laggy at all and it's running normally before freezing.

This started in mid december. Have anyone else of you had same kind of problems? How to fix this?

I could say a few things, you can

A. Clean out the PC case, dust can slow a PC down.

B. Clean up the registry, a clean and error-free registry boosts the system. There are a few tools that do so.

C. Defragment your hard drives at least once a month

And if that doesn't work,

D. Upgrade the weakest part of the system (the least powerful) to a newer part
or
E. Reformat the whole PC and start from scratch (you will lose all your data)

I would suggest you check the event viewer before doing anything else (Start->All Programs->Administrative Tools).
Note the time of the freeze and investigate what applications were running at the time. Go from there.

I'm telling you this cause I had similar problem myself (freezing) and after event viewer told me googleupdater was trying something, I went to investigate. Turns out I uninstalled it long ago but that didn't stop it to put itself into windows scheduled tasks, with the mission to update itself every hour of every day :detective. No problems after it got purged out of my pc, which was two-three weeks ago.

In your case it could be some applications clashing or whatever, doesn't hurt to check

Although, it must be said, 5yr old pc can show problems that come with aging without any symptoms and suddenly . Do a hard disk scan to check for CRC errors, memory test, graphic card temp test, etc... whatever you can think of. Maybe you could pinpoint the problem.

i have had this problem in the past with shoddy power (and power supplies)...

then again, it could easily also be a bad video card...

Same as Bunder, I had a 4 year old powersupply, and it started going mad for some reason, shutting off all the time, then I bought myself a new one like 0.5 years ago, since then there was no problem.

Ask one of yer friends if you could borrow their powersupply for a test and check if it freezes still. If it doesn't then buy a new powersupply