This is a new one on me:
NW65 server hosts BM38 proxy. All clients are XPSP2, patched, using client trust, preferring Mozilla Firefox browser, proxy is manually set in the browser.

User {studentuser} attempts to connect to, gets popup error message " could not be found. Please check address." Not a 404 in the browser window; looks like maybe a DNS error. User {studentuser} CAN go to on same client.

User {localadmin} logs in to same client. When using the local admin user, Firefox connects just fine to, as well as Admin logs out, goes back in as limited {studentuser} and cannot connect to k12 address. Admin checks another computer right next to affected machine; other computer can access both sites. Admin pings, gets four timeouts, but the IP that gets echoed back does go to a blackboard site (albeit not the k12. site). Affected workstation cannot ping Only diff. between the two is that affected workstation is wireless, other is FE.

Admin tries IE on affected laptop, CAN connect to Tries Mozilla again, CANNOT connect to Logs back into affected laptop as local workstation admin and gets both sites, both browsers.

I can't even imagine. Some kind of strange redirect on Blackboard's end? Checked HOSTS file on affected laptop, checked Mozilla settings, same on both machines, both use same DNS servers and, of course, both users on affected laptop use same DNS servers, same everything. Really, really mystifying. Wondering if anyone has seen anything of this sort, or if anyone is particularly familiar with Blackboard's back end...?