Pandora Streaming issue

I have been having a strange problem with Pandora that I cannot figure out and I have been beating my head against a wall for a week now. I believe it is a firewall issue. Here is what is going on .

All windows7 users have no issues with pandora it works great. All windowsXP users have serious problems. and just cant use pandora. mostly the player just wont load. they get a Blue pandora screen with logo and a spinning circle. and eventually get a taking too long error msg.

I have tried all of the pandora trouble shooting tips for FireFox Chrome and IE. even happens with a fresh XP install.

Contacted Pandora support and they cant help

I have tried everything I can think of for my Astaro Firewall which is an ASG220 nothing.

If I bypass the firewall pandora works instantly.

I have added and exceptions for Web filtering using the URL and the entire IP block Pandora uses and also no change.

Any Thoughts or Ideas would be appreciated.. Also sorry if I forgot to mention details im tired.

Thank you.