Can't access gmail online

For the past week I have been unable to access gmail online. I am running Windows XP Professional, and I have tried with both Firefox and IE. I am behind a firewall at a client site. They have websense, but when pages are blocked by websense I get a message from websense telling me so and my coworkers are able to access gmail with no problems.

When I type in gmail.com I get redirected to mail.google.com/mail/ but from there I get a "problem loading page" error saying that firefox can't establish a connection to the server.

Here is what I have tried already, to no avail:
- flushed dns cache
- stopped, restarted dns cache
- successfully pinged gmail.com, mail.google.com, (made sure the IP was registered to a google block, so not a redirect)
- verified my hosts file has only localhost
- ran spybot to remove spyware/malware (nothing out of the ordinary found, all removed)
- ran avg anti-rootkit, no rootkits found
- run symantec antivirus, no viruses found
- removed installation of google toolbar
- disabled greasemonkey and all firefox extensions

What else can I try? I'm out of ideas.

Thanks!
Jet

 

Forgot to add another thing I have already tried:
- Deleted all temp files, cookies, and history for both browsers.

 

Thanks Halo.

The only software firewall is the Windows firewall, and I can't change the setting on that since it's a work computer.

Don't know about using a proxy for internet filtering other than websense. It sounds like it's possible their admin blocked it since I usually do leave it up all day long.

We don't have a username/password for internet access, and we're not on their domain since we are contractors. I use gmail legitimately for work, so this is no fun!

I've got access via IMAP now though, so at least I can read my mail.

Thanks much!
Jet