first try
1. Click Start
2. Click Run
3. Type in the following: C:/Program Files/
4. Look for your Diablo 2 folder. Could be named Diablo, Diablo 2, or Diablo II
5. Open that folder, and find all files starting with "bncatche" (There may be several)
6. Delete all of those files
7. Run D2 Normally (Note: a new bncatche will appear, do not delete it)
if that doesnt work check out this guide
http://forums.d2jsp.org/index.php?showtopic=12558087&f=21