Without more info, could be many things. If you are putting 2k onthe machine, do a clean install (ie, backup first - you should anyway), not an upgrade from 98. Otherwise you may keep your problem. But, problem could be hardware related - if so, 2k install will almost certainly be problematic & may not complete (& if it does, you'll get problems).
So, probably good idea to diagnose & fix problem before you install 2k - more details please.