Oh, it certainly doesn't look very nice.
A few questions:
1. Are you using the latest version of avast! (i.e. build 396)?
2. What language version is your Windows 2000 installation? English?
3. Do I understand it correctly that it goes this way: you run the scan (of your disk or some folders). avast! scans the files and finishes "correctly" (i.e. without any error messages). Then, it displays the results with a number of "files not scanned". When you click any of the file in the "Results" window, you get this "Buffer overflow" message. Am I right?
4. Can you please turn on the creation of the report file and try to scan again? (Go to program Settings, select "Report File" page, check "Create report file", and make sure the items "Hard errors", "Soft errors" and "Skipped files" are checked in the options below.)
Those filenames shown in the results windows are really strange... seems like cross-linked folders or something like that. I would like to know the exact paths, but they are clipped in the user interface - the report file would be better I guess.