I am using window 7 enterprise my computer can recognize the sony memory stick pro duo adapter with 1 GB card but cannot open it neither can format it. please tell me any solution.

SOURCE: Memory Stick Pro Duo 8GB on PsP

Two possibilities.
1. The firmware on your PSP is too old to recognise the 8GB (only recognises up to 4GB).
2. If firmware is up to date you have a fake memory stick (easy way to check is to check the info for the memory stick on your PSP if its says that MAGIC GATE is unknown rather than supported then it is fake.

The fake ones typically double compress the data so that it appears to have 8GB when in reality it does not.

SOURCE: Sony memory stick PRO Duo is not working

try formatting it on a pc in FAT file system or run a deep scandisk

SOURCE: formate memory stick

how can i formate memory stick pro duo 1gb

SOURCE: Misfunctioning 4GB memory stick pro duo

Are you formatting it with your computer or PSP?

1. Push the little HOME button on the bottom left of the face of the unit.
2. Use the arrow keys to move to the SETTINGS area, then move the up and down keys until you get to System Settings.
3. Once you are there, click on the "X" button and scroll up and down as needed to find Format Memory Stick. Click on "X" again to select that option.
4. The Sony PSP will now confirm that you want to reformat the memory stick (which removes every file and game save thereon, of course): choose yes and it'll format in just a few seconds.

SOURCE: sandisk 2gb memory stick pro duo wont format

it means it is containing some virus...try to format it with some other system..but it is a frequent problem...try to delete the files while in the phone and format using the computer...its better to claim warranty if it has....
is this cleared your problem?