Muzzle Flash,Bullets/Holes/Tracers Disappear

For some reason whenever i'm on FFA even sometimes on TDM eventually after a few mins all bullets/tracers/bullets holes in walls/muzzle flash disappear.It looks like me and every1 else is shooting BB guns,it's much harder to aim when i cant see these things

My PC didn't use to do this and iv tried new drivers and reinstall didn't work..
Current Specs are:

CPU: AMD Athlon 64 2.2 Ghz Venice Core [Single] OCed to 2.7 Ghz
Ram: 1Gb @ 333mhz aka 133
OS: Windows XP SP3 with all Updates + Latest DirectX
Video: Ati Visiontek Radeon X1600XT 256 GDDR3 @ 1.38Ghz/Core @ 590Mhz
MotherBoard: Biostar K8T800-A7A

Pretty old stuff but i play it on all high at 100+ fps,but yeah it's just weird why it's mostly in FFA....