Like Redcrown and Phil Indeblanc, I am also finding that C1Pro exhibits some strange behaviour running on my 64bit Win7 machine. Being new to C1 doesn't help!
The first issue I became aware of was that auto mask wouldn't work, as I've previously reported here. It was suggested by Phase support to un-install v7.1.4 and re-install v7.1.3, as they thought it would work better with Windows. Unfortunately not, and this is ongoing.
The next issue I discovered was with the import dialogue browser. If I processed a raw in C1 and exported it as a tiff, and then imported that tiff back into C1 its thumbnail and file name would appear in the importer browser, as you'd expect. But if I imported the tiff into Lightroom, and exported it again, that tiff would not show up in the importer browser when I tried to import back into C1, only a placeholder and filename, but no thumbnail. Similarly if I opened the tiff in Picture Window Pro and saved it again, that tiff's thumbnail would not show up in the import browser. Now what the difference between these tiff files is I haven't a clue, but C1Pro seems to be very picky. This has no effect on actually being able to import the files into C1 however, it's just that one can't see from the import dialogue what is going to be imported. This issue has been forwarded to R & D.
Lastly, I've just noticed that the focus mask doesn't seem to work with RW2 raws, though it seems to, after a fashion, with RAFs and ORFs. And neither does it work with their associated jpegs. I need to investigate this further and go back to Phase support again.
Disabling hardware acceleration makes no difference.
I very much like the results that the raw processing engine of C1 produces, but the application's supporting software does seem excessively brittle on my machine. I do wonder what else I'm going to find that isn't working. I'm guessing here, but I do wonder if C1 has been designed for the Mac and the transcription for Windows is less than perfect. I can't test that as I don't run a Mac. I find it strange though that these issues with Windows don't seem to be common, so perhaps it is a particular hardware/set-up issue, but I'd sure like to know the cause. I am somewhat disgruntled as having bought the Pro version I'm finding that some of its features aren't working properly, which for a mature application just shouldn't be the case. I might as well have gone for the much cheaper Express version.