I have also been experiencing this problem over the past 3 or 4 days, in Denver, CO.
I have had pocket pc's which would only work with prl 1050, one that would not do data with any evdo prl, but would do 1x with 1040 loaded. Mostly I have been getting invalid username/password.
It's really frustrating... hope it's a temporary problem.
I will say, I do not like the new PRLs, #1006, and especially #1007. Call me crazy, but those PRLs have an entourage of problems.