Google Maps GPS not working anymore iPhone

Hey all,
The GPS in Google Maps (the feature allowing me to indicate where I currently am by placing a blue dot with a blue concentric circle around it on the map) stopped working. It used to work perfectly, and now it only works very, very sporadically. Usually it shows a wrong location (one mile off, 2 miles off...) and stays there even if Im moving. If I try to turn the feature off and back on, it does not search or try to communicate with the GPS - the phone shows no activity, and it still shows me the old, wrong location.
Any idea how I can fix that?
PS: Not sure if this is related or not, but Shazam is no longer working on my phone either.
Mac Pro 8 Core - Mac Book Pro Santa Rosa - Logic Pro 8.0.2 Mac OS X (10.5.4) Metric Halo ULN2 - Apogee Duet