OK, which version of RA? The newest is 1.50.
Have you installed an older version of RA prior to the most recent?
Did you install your current version of RA over the previous one? That's a no-no. Always install RA into a clean version of DW with the 1.04 patch.
Otherwise, you might try doing a re-install of RA. Start with a clean install of DW patched to 1.04. Extract the RA installer and the data folder(s) and place them in the MAIN DW folder. Run the installer-
it usually takes a while even on a fast machine- make SURE you see the installer's final "press any key" message. Try it again.
It sounds to me like something(s) didn't install the first time. This tends to mess up different platforms in DW/RA and the P-3 is one of the prime candidates to get screwed up.