I'm running a Windows Sharepoint Services (v2) Team site under Windows 2003 Server (standard), using IIS6 and MSSQL 2000.
I can access the site fine from my laptop as can my work collegues. It also works from my home PC, in IE5, 5.5 and 6 + FireFox 1.0.
However, people browsing from two separate locked down corporate networks always get IIS 500 error pages when they try to login to the site. The username/password used in all cases is the same.
I'm looking for some pointers on where I should start looking for the cause of this problem.