gps giving wrong directions

[steve30b]

some times my halfords pocket pc and gps system (navman) gives me wrong directions,i was driving down the M1 back to sheffield from nottinghamshire last night and twice it said to me (prepare to turn right)
(please turn right now) when i needed to carry on on the M1 can any one explain why this happend.or do these units do this sometimes hope someone can cleare this up for me..also can i use the tom tom software with my medion pocket pc.

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