Update: In addition to the original "problem" PC (W/7) as described, subsequent trials with the other board resulted in "abort mission, an error has occurred". So, in neither case were they properly recognized - one wouldn't reprogram and the other gave a wild error message.
I've tried it on three others:
Dell Netbook/Xp Used for general Ardino programming for several years. Won't decompress files without password request - copy and paste workaround suggested by one of your users results in a copy of Ardino 1.0.4 that crashes on opening. Several attempts. Driver seemed to install, but it's not useable since the sketch compiler won't run. (The previous version from Arduino.cc runs fine still)
Dell Dimension 4600/Xp Has previously been used for Arduino work but currently just a backup machine.
Download from Digistump showed as corrupted and un-decompressible. Used transfer copy of software that worked yesterday and drivers loaded okay, and recognized chips (so they're not dead), but on attempted upload I get the following error:
Binary sketch size: 758 bytes (of a 6,012 byte maximum)Running Digispark Uploader...Plug in device now... (will timeout in 60 seconds)'C:\Documents' is not recognized as an internal or external command,operable program or batch file.
And nothing seems to fix this - changed the "preferences.txt" settings in the app data\arduino folder. no luck. Note that this has previously been used for Arduino work but has most of the software gone. Drivers are likely still in there somewhere though (read on).
Newish HP Pavilion Laptop (W/7) with no Arduino history - works wonderfully on both boards. JOY!! The only common factor I can see here is that the previous three machines have been previously used for other Arduino work. Possibly a driver collision/problem??
So, is there some way to uninstall the "old" drivers or other causal factors and put the "new" one in place to see if that's the problem? Or am I barking up the wrong tree??