On a clean install of Windows 7 32-bit, Office 2010, and Microsoft Dynamics GP 9, I received the file not found VBA6.dll error as soon as I'd made my first VBA modification:
I tried a few fixes including downloading and registering a new copy of the VBA6.DLL, but the error persisted.
Then I found a post by Beth Gardner describing the same problem. The resolution involved both a registry edit and the deletion of several files from the Dynamics GP folder.
The solution worked perfectly for me and I expect to see this problem more in the future as it seems to be related directly to an install of Office 2010.
I could not replicate the problem on a clean install of Windows Server 2008 R2 on which I had not installed Office 2010.