gps position unreliable

[bigstu25]

This might be a stupid question but my knolege of gps and how it works is limited.I have been using tomtom 3 on a dell axim blue tooth for a year no problems.Today i had a problem all day was not able to get a gps position it was being used in a fiat van and a mondeo car no problems ever before. I was driving in glasgow i have been reading adout some windscreens having problems what i wasn't sure if because of the weather being realy hot does this cause any problems in recieving reception i am using standard tomtom blue tooth reciever.

[Stevie]

Is tomtom set to the correct com ports?
Click on start -> tomtom GPS -> GPS (bottom left)

[bigstu25]

I tried again today i looked at gps status it was getting about 5 sometimes 6 of the satilites to plot position but were very intermitent all it took was to move the reciever a couple of inches and would realy nok signal of.i am tacking that i wouldn't recieve any if it was conected to the wrong com ports.
What i did notice on the tom tom reciever at the back on the side in the midle next to where the charger cable goes in a rectangular bit that has gold colour strips there is two at either end and posibly looks if there are two in the midle missing i am not sure if this has anything to do with recieving signals and that reciever is damaged i was using a gps that is instaled in the van i was using today and had no problems recieving a signal from it would apreciate any other advice thanks