Right-click not working in Outlook 2003 SP3

Hi,

First post - I hope it's in the right place

I'm having an issue with Outlook 2003 where the right-click shortcut menu doesn't work. I have Googled this, and have found a short-term fix by clearing the Forms cache (or something like that) but every time I shutdown and restart Outlook the problem returns.

I have also tried deleting FRMCACHE.DAT and starting Outlook in safe mode - neither of these seem to resolve the problem.

System info is below:

OS Version: Microsoft Windows XP Professional, Service Pack 3, 32 bit
Processor: AMD Athlon(tm) 64 Processor 3200+, x86 Family 15 Model 79 Stepping 2
Processor Count: 1
RAM: 3006 Mb
Graphics Card: NVIDIA GeForce 6150 LE , 256 Mb
Hard Drives: C: Total - 147777 MB, Free - 37043 MB;
Motherboard: Dell Inc, 0HY175, A02, ..CN708216A4K0OT.
Antivirus: Kaspersky Internet Security, Updated: Yes, On-Demand Scanner: Enabled

Any ideas? - help would be appreciated.