I get an error message "invalid character in line 1" when loading my ISP's webmail program

Question

I've tried ALL possible solutions offered in the Firefox articles without success. No problem with any other web sites, just the web mail site offered by the ISP, which blames Firefox. However, I can load the web mail site in IE (don't want to, though). The web mail program first gives the error message then allows login information to be filled in, then starts initializing and gets to "90%" of initializing then freezes while the wheel goes round 'n' round. Any ideas?

Answer 1

In looking at the console (first time - I am a naive user, not an expert) I find that there is a 404 error appearing on the 6th line of puts and gets in the console. All subsequent lines are 404 file not found errors, until the computer hangs. Here is the reading of the 5th and 6th line:
16:01:02.248 PUT https://www.webmail.bellaliant.net/ajax/multiple [HTTP/1.1 200 OK 443ms]
16:01:03.366 GET https://www.webmail.bellaliant.net/ox6/v=OEU5Kkd/plugins/com.openwave.richmail.userguide/lang/en_US.po [HTTP/1.1 404 Not Found 32ms]
Now I have found a virus on scanning the computer with Bitdefender, and I believe the problem may be caused by malware attached to a script library. Bitdefender says it cannot clean the file. Here is the message from Bitdefender:
c:\users\Tim\AppData\Local\Temp\DI\ValidationSctiptLibrary.dll has been detected as infected. Bitdefneder could not clean this item. Your computer is not virus-free. Virus name:Gen:Variant.Adware.AdGazelle.1
Cor-el suggests cleaning the Firefox memory with "forget about this site" - will that remove the problem?