Mercurial commit doesn't work: File Error - Cannot write message file

After updating to QT SDK 1.1.3, commit to Mercurial stopped working.
After entering my commit message, selecting files to commit, it gives out popup error dialog:
"File error"
"Can't write file C:\Docume~1\username\Locals~1\Temp\qtcreator-hg-fl2176.msg. Disk full?"
After that in specified folder a zero-sized "qtcreator-hg-fl2176.msg" file is created, as well as a backup message file with name like "qtcreator-hg-fl2176.msg.sv2176" with proper content of my commit.
Repeating the attempt creates more copies - "qtcreator-hg-fl2176.msg.xC2176", etc.

Also, you can only abort the above error dialog by removing all files from commit - closing the QT Creator doesn't work.