Windows update issue

Hi,

I have a winXP Pro SP3 with IE8 laptop
We have also 2 internet connection (ISP-1 and ISP-2)and a Sonicwall pro 2040. ISP-1 connection we use for servers only and ISP-2 for users.

When laptop is on ISP-2 WUS won’t work, but when using ISP-1, this will work.
Strange thing is all other network computers using ISP-2 can perform update. So i don’t think this is a firewall issue.

following the error code on WUS page, it informs me that it’s an connection problem, trying other solutions on the net didn;t resolve it.

Has anyone any ideas what is goin’ on or anything else i can try?