> Try a clean installation.

A freshly extracted archive does the same thing for me.
Right click- Extract to /cmp354 and launch cmpro.exe, renders the same error.

The OS is XP Pro SP2, indentified as Ver. 5.1.2600, freshly installed with "Files and Settings Transfer Wizard" applied to it after the install to bring back most of what I had previously. The CLRMAME Pro worked last time I used it, it's all kept on a FireWire drive and moved between PC and Mac. It was V3.44 and I saw that a new version was released so I moved all the content from that over my existing stuff and it does not run. I tried the old version on a different drive, same thing. Also extracting a new one and just using it right where it was extracted results in the same error.

It happens right when you launch the .exe.