Quick question...
 

First off, sorry if this is the wrong place for this, but...

Whenever I open up the inventory window while playing, my game literally slows to a halt, and I can't do anything except closing the inventory through keyboard shortcut... this seems to be the only problem, as the other windows work fine.

Does anyone know a solution to this?

How long does the hold-up last? I get the same thing, but it is "momentary" (roughly 15 seconds). I assume, though am not certain, that it has to do with the server and your system needing to communicate (synch-up) for your equipment. I could be way off the mark though.

Maybe its a lagish server or has bugs...

You playing on a server thats on 24/7 except for maitnince and power outages? (like my server)

I recommend that you get more RAM if your system slows down, or try looking at your inventory in another server and see if it is just the server.