problem with computer

I have trouble with my windowsXP and CoDUO. Thought it is because something in comp eg graphic card. Applications (when I do not play) and when I play CoD it starts to freeze, and during play ping jumps to 999 for a few seconds, pop! and I am dead... it happens nearly everyday already from some time ago, but linux seems to run without problem (I have 2 systems on my comp) so I try to reinstal CoDUO on linux platform, but again now I have problem with linux xwine... can't install CoD it says ti is not compatible... today update xwine hope everything will be ok.

Maybe you know what cause this kind of problems?

ps. during play I do not download anyhing and do not use an other program like msn or antivirus or firewall it's only CoD. Comp returned from service, they said everything is ok (noo!!it isnt!). I checked my system for viruses, reinstalled all system from scratch and it happens again. My english grammar and vocabulary sometimes is shit, hope you understand what I wrote...

ps2. specs: AMD Duron 1.6GHz, graphic card ATI Radeon 9250 256MB

I think what you're saying is that your ping jumps during COD, but otherwise everything is good. Is that right? If it is, you MUST make sure that in your COD multiplayer settings that your connection is the correct one (ie. LAN, cable, 14.4, etc.). If the wrong one is set, it will make your ping jump to 999 and on occasion it will interrupt. Check that to make sure you have the right setting.

If not, are you connected through a LAN or a router or anything like that?

Mrpants, thank you for answering. Ping jumps during COD but otherwise not everything is good. I have cable connection. No router. My modem is connected with modem of my internet provider (local TV network) who is behind firewall. Checked that and I am sure that in COD I have right settings: cable.

It happens nearly everyday, but not regularly. For example one day I cannot do anything with computer, the other day I can play COD 1 hour, then something happens and computer starts freezing, then after 1 hour or more somethings unlocks and again everything it is ok...

During the game I experiment also with console commands like: "/rate", "/com_maxfps", "/com_hunkmegs", "/snaps, "/R_PICMIP".... even launch "/seta cg_lagometer 1" and watch interruptions then increase rate or decrease snaps, this helps a little but not when high ping jumps starts... then any idea?