Error opening form with image control

I have a form that on some workstations will not open with the following
error:

"The form you selected could not be displayed. You don't have appropriate
permission to perform this operation"

If I try opening the form from an OFT file, I get the error:

"The messaging interface has returned an unknown error. If the problem
persists restart Outlook".

I removed a the company logo from the form - In an image control - and this
fixes the problem.

Any idea's what might cause this problem?

Thanks,

Stephen.

This problem appears to only happen with GIF and JPG images? Not sure why,
has anyone else seen this sort of problem?