Try this- with the windows disc inserted, enter the following command:
for %P in (E:\i386\*.tt_) do expand %P %windir%\fonts
I wasn't able to actually test that, so if it doesn't work you can try it with each individual font file; by default XP's font is Tahoma (for things like menus, title bars, buttons, et cetera) so you would expand the original tahoma file:
expand -R E:\i386\tahoma.tt_ %windir%\fonts\tahoma.ttf
expand -R E:\i386\tahomabd.tt_ %windir%\fonts\tahomabd.ttf
However, all that said, I don't think ccleaner actually deletes the font files, but manages to mess up the registry entries for fonts. In this case it could be that the font files are missing and/or the default font value is no longer valid (or points to something like Marlett which only has a handful of actual symbols; unknown symbols are drawn as the box which you noted).
In that case, you can reset the default font using this registry script:
http://www.kellys-korner-xp.com/regs_edits/defaultfont.regyou can either mess about to get it started via the more readable command line (by say putting it on an external drive, using start G:\defaultfont.reg and then clicking OK (or pressing Alt+O or Alt+Y... I can't recall wether the actual message uses OK and Cancel or Yes and No).
at that point it will give you a message (that I imagine you wouldn't be able to read) so assume the best and try rebooting. I'd suggest copying the tahoma fonts using the earlier command prompt commands, then trying this method.
Another option would be to try
High-Logic's Fix Font's Folder Tool; you would get this to run the same way as the registry script, but it's a program file. simply launch it by typing the path (for example, if you burn it to a CD and your CD-ROM is E: you would type E:\fifofo
The program will launch, and of course you won't be able to read a *censored* thing in the disclaimer thing. Anyway, dismiss that first dialog and the click the first toolbar button on the top left, which should fix any issues ccleaner may have introduced registry-wise that corrupted the display.
Hope this helps