When I try to enable a newly uploaded theme I always get an error

The [biglongnumberandletters]~default theme was not found

Actually, even If I try to enable Stark or Garland I get the same error. I'm installing on a shared host, can't identify any permission problems, and am basically stumped...

Comments

Is this on a new install? the default bartik theme enabled?

have you tried running update.php?
do you have a default theme forced in settings.php?

Yes, this is a new install... although I installed a few times prior with this same error - on this same shared host.

Yes, the default Bartik theme is enabled.

I just ran update.php - but no change from previous problem.

I believe settings are *not* forced in sites/default/settings.php - plus I checked default-settings.php -- all seemingly commented out, and anyway, they say Garland so if they were, then I'd be stuck on Garland, so,...

I'm upgrading myself to double-befuddled status.

Finally got things working.
Since my installing on shared hosting account just does not seem to work, I decided to use the softalicious installation thingie and see what happens. I did, and all error messages disappeared, themes install and activate without problem, etc.
There's probably a lesson here, somewhere,...