Sony "Access" Message

[brewers9]

when I install my memory stick into the camera ( DSC-H2 ) it comes up with an "access" message on the screen and will not let me look at the pics I have taken...... any ideas?? it works with my other 4mb stick no problem, and this one worked last week when I took the pics, now I cannot see them to download them....... trip pics so really really cannot lose them..... :(
thx for any ideas........

:)