We need a little bit more information...
Some system specs might be nice. Maybe what was included in the error report.
However, to me, this sounds like a problem with the game on your PC, or your PC/Hardware. Sounds like the game has crashed due to some error of sorts. What happened to you wasn't a disconnect, it was a crash of your GW client.
What I would do first of all, reply here with some system specs. Go to start, run and type in dxdiag. While I am sure your comp is fine if you have been playing for years, We'd still like to know what your specs are just incase we can offer a suggestion to upgrade the PC or a part within the PC.
There could be a number of things to cause a client crash.
Bad/Dying memory could be one, any portion of hardware going bad, a dust-clogged PC can restrict airflow and can cause overheating of the GPU (graphics) or CPU (processor).
First thing I'd do is open it up and see if it's clogged with dist, if it is, blow it all out and give it another shot.
Corrupt GW.DAT can be another error, which personally, I'd do after I cleaned out the PC of dust if it dosen't fix anything.
Corrupt GW.DAT: The GW.DAT is corrupt/can't be read right, to fix it, one would delete it and reinstall it using the -image command.
On Windows XP (I don't know Vista or 7's default program path) Navigate to "C:/Program Files/Guild Wars/" you can even type that in, in a Start>Run command. This will show you the GW folder. Then delete the GW.DAT file, the one that is usually over 3 GB in size or something like (3,000,000 KB) as Windows XP seems to show it in title icon view.
Delete it... then go back to your start>run command box and type in:
This will redownload everything, which is 3+ GB of information. On a dial-up this is a bad idea, on a broadband connection, expect to wait an entire day or just do it before going to sleep at night.