Distribution/Version: XP Professional 2002 (Spanish)

This happens every time you do something involving thumbnails (opening and
saving files, or previewing files in the Open Image dialog). If your username
contains accented letters, The GIMP will show a message that looks more or less
like this:
"Failed to open <<C:\Documents and
Settings\Username\.thumbnails\normal\gimp-thumb-xxxx-yyyyyyyy (invalid
encoding)>> for writing: Invalid argument"
I've had this problem since I upgraded to version 2.2.4. Funnily enough, version
2.0 and older didn't have this bug.