Does not take picture 2

using paint shop pro to browse memory stick via a generic card reader as always do when suddenly card no longer recognised and no drive is visible any longer. Upon putting card back into my DSCP73 I get the dreaded C1301 error and as your drive no longer visible even with win explorer no chance of a format.

I restarted the PC and plugged back in the card reader to find that both of my cheap card readers can now see the drive but cant access the data.
However this now allows right mouse click - scandisk with "fix file system errors". The drive was half full of totaly fragmented data which I could then defrag and finally delete. Upon placing card back into camera, fault has gone and everything is fine.