Why does Premiere Pro CS3 no longer import .psd files?

Question

Over in the German forum, BjoernG has already asked this question as of this past June.  He's gotten no answer, so let's try it here.  Like Bjoern I use PPro CS3.  Mine is on WinXP with all updates.  I import PSD files as keying masks.  I've never had a problem until this evening (27 Aug 2014).  I tried to import a mask I've used many times before.  And it has always worked before.  Tonight PPro refused to recognize .psd as a supported file type, so it didn't show in the import folder file list.  When I told PPro to show "all files *.*", it showed the file.  When I selected it, PPro even showed the "import file" window, then displayed the "File Import Failure" window with Error Message:  File format not supported.  See the picture.
This is a file I've imported into many previous projects with no problem whatever.  In fact, I started with a project file from last year which showed the mask file in the project assets but offline!  Even though the file had not been moved.
If PPro CS3 is as obsolete as Adobe claims it is, then who's been messing with it?  And how can we get it "unmessed"?

Answer 1

I couldn't imagine what any of those steps would do for my problem – but I didn't have a better idea so I tried them:
> If Premiere is acting weird, restart computer.
It's a laptop, so it was off all night.  I turned it on this morning.
> Hold down shift+alt while opening Premiere.
If I hold down shift-alt before clicking the desktop icon, all it does is select all icons from top left to the Premiere icon.  It does not start Premiere.
If I press and hold shift-alt immediately after clicking the icon, Premiere displays every tiny module it loads rather than summarizing.  I held shift-alt until Premiere was fully up and idle.
> Then empty all media cache.
I did that.  As I write, Premiere is busy reconstituting all of that.
Then finally, the acid test:  Try to import a .psd file.  Bzz-z-zt!  Still claims it's an unknown file type.
> jpegs do not have transparency. You can save as png instead.
I'm using it as a track matte key, so white is equivalent to transparent.  I do have to select "matte luma" instead of "matte alpha" in the effect.  I'll save your advice in case I ever do need transparency.
Follow-up:  I checked my other licensed copy.  It accepts .psds just fine.  I checked Help About for both; they're identical:  3.2.0 (374).  So the problem must be in an internal setting, an external influence, or a defective module.  And remember, it's not just me, Björn in Germany reported the identical problem in June.