Double-ugh. It looks like the best results are to actually to the drvload before the net start. Sorry! That should rid the error "...cannot find the specified file..."...Ugh. Are you quite certain that the drvload step was performed in the tests that failed with the message above? I was fighting with this for quite a while until finding that the precise order of events in the first post in this thread appeared to work consistently. If you're certain that the steps were completed in this order and still yielded this error message, I'll have to try to reproduce it...
Still investigating the file expansion freeze...