My Game Locks Up..

Matto-67

<div class="IPBDescription">after about 2-5 mins..</div> Ok, i connect to NS, select a server, everything seems fine.. i load the server and i get started.. then BOOM i lock up.... the only way to exit is to restart my com by Alt-ctrl-delete... this has started a few weeks ago... really pissin me off... please help me!! i dont know much about computers... alls i know is i got

900 mhz
256 mb RAM
ATI 9200 graphics card
and i have Windows 98 plus...