PPCGeeks - Trouble with storage card after sprite backup

I've got a Tilt and I used to read the microSD card in my PC trough a card reader. Two days ago I performed a backup using the Sprite application and for some reason I can't access the card from the computer anymore. I tried to backup the card to the PC using sync connection. I went to Sprite backup settings and set it for PC but it didn't do it. In the report said it failed due to "unable to connect to host server". I want to upgrade the msd card from 4 to 8G and I cant back it up. Any help would be appreciated