TomTom 710 locking up

Had this problem several times now, and its getting a tad annoying !! I power up the unit, the splash screen appears, then changes to an image of the TomTom, and refuses to let me navigate, with the picture frozen, it won't even let me switch it off, I know about the paper clip trick to reset the unit, which i have had to do several times now.
So do i have a faulty unit ? or in the words of TVR salesmen "They all do that Sir" .............But do they?
Please advise guys, as my confidence in my newly aquired wife/route finder in the car is dwindling a bit.
Dave