I can also confirm this behavior in ComboFix, after running it, the <TAB> button in cmd.exe stops working and CodePage is changed to 1250.
To resolve the CodePage issue, you can change it under HKEY_CURRENT_USER\Console\CodePage but still, ComboFix should check if the value is a sane numeral (16 bits at most, and not null/zero) and not missing. If missing, replace it, else, don't touch it.
As for the tab button, CompletionChar should always be "9" in HKEY_CURRENT_USER\Software\Microsoft\Command Processor\CompletionChar
ComboFix should replace it with "9".
Edited by boopme, 21 February 2011 - 03:39 PM.
Moved to Antivirus discussions.