AT&T microcell . . .

[ChileRick]

has been working perfectly., then not . . . .searching for signal. This occured and the same time my Pandora disappeared.

was there a software upgrade that may have caused this?

[eljefe2]

MicroCell and Pandora both still working here, for whatever it's worth.

FiOS 74/35 package with Actiontec Rev I router.

You might try the at&t forum, posting specific symptoms you're seeing with your MicroCell:

http://forums.att.com/t5/3G-MicroCell/bd-p/3gmicrocell