If you experience a crash giving you the message "Error Decompressing Sprite," you should first attempt to uninstall the game (using the "Add/Remove Programs" Control Panel button) and reinstall the game fresh.
If that fails, check our CD Performance page for solutions to possible disk-read errors. Manually copy the file D2Char.MPQ from the Diablo II: Lord of Destruction play disc into the Diablo II: Lord of Destruction folder on your hard drive.
If this error persists, please send your d2#####.txt file from the Diablo II: Lord of Destruction folder to Blizzard support, so that we can better address your problem.