We were seeing this exact error; however, our users are using a Citrix client to connect to a Windows 2000 terminal server, and would get the error anytime they tried to run the Visual Basic Editor out of any Microsoft Office (2000 and 2003) application. Administrator users did not see this problem.
To figure out the problem, we used the "regmon" utility (available at
www.sysinternals.com) to watch registry queries. We compared the results of a successful attempt by an Administrator with the unsucessful attempt of a regular user. We saw an "ACCESS DENIED" message on the below mentioned key immediately after an attempt to access the VBE6EXT.OLB file.
To fix the problem, we granted the "Everyone" group "Full Control" permissions on the HKCU\Typelib\{0002E157-0000-0000-C000-000000000046} key in the windows registry of the terminal server the users were connecting to.
Hope this helps!