Unfortunately its a known issue with the Treo Pro, my friend
Next time you're out in an open area, turn on google maps and wait AT LEAST 5 minutes. If you still don't see a GPS signal then you may have a faulty radio. You might be able to check with whoever you bought the phone from to see if they'll help you out, but that's a BIIIIIG YMMV.
Other people have had luck with an application called "Quick GPS", but it hasn't helped me any. It sounds stupid but usually I just fire up google maps a minute or 2 before know I'll need it
Hopefully someone MUCH smarter than me will have a better answer for you (and me)
Best of luck....
jm