Firefox 10 corrupting attachments?

We've recently discovered that Firefox 10 cannot send any attachments through WebAccess, as they all end up corrupted (receiving is no problem, only sending). All other browsers, including every previous version of Firefox, work just fine. Has anyone else experienced such behavior? Can anyone send attachments via WebAccess 8.0.2 HP2 (running on a fully patched SLES 10 SP2) while using Firefox 10?

Thanks in advance.