(See the best response by Lummox JR.)
Cause: No Idea
This happens whenever I try to join a server. Rather than a dreamseeker window appearing instead dreamseeker starts to run in the background and, very slowly become big enough to crash a 8gb computer. tried uninstalling and reinstalling Byond, and it didn't work, I have been using byond for a year on this computer.

Here's a picture of it filling my computer. 1111307422733176923/wan.png
Through testing I figured out that if I click join once only a single instance of dream Seeker appears in the background but its still trying to kill my computer.
Best response
This really smells of something being wrong with your installation. In particular it sounds like somehow the byond:// protocol has gotten linked to Dream Seeker instead of the pager, which is something that shouldn't happen anymore since it was changed a long, long time ago.

I suggest doing a full reinstall of BYOND. Uninstall the program (but not your user data; the uninstaller will leave that alone) and reinstall.
Uninstalled using the uninstaller, installed again, still trying to blow up my computer.
I moved by byond user data folder into a diffrent location and now it works, although there goes my user data.
You can probably restore various bits of it. Guessing something went way wrong with your configuration.
ur cool lummox good work