Cleaner wiping out Word 2007 shortcuts?

I'm using Office 2007 on a Windows XP SP3.

I write frequently with foreign characters. So, I go into the Ribbon's "Insert Symbol" > Shortcut Key and assign a particular shortcut for a symbol I use a lot: for example, pressing ALT + e for ?.

Now, however, I've noticed that every couple weeks or so, the shortcuts are getting wiped out; and, Word doesn't seem to remember them anymore.

I've got a good anti-virus/etc. program installed, so it's probably not a virus. I used to own an old laptop with Win98 and Office 2000 . . . and (need I say?) never had a problem with this.

I do have CCleaner installed, and wonder if it could be that.

Any ideas?

Untick/disable the cleaning of Office in CCleaner.