Must read before posting: How to post your System/Network information
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Then we can help you.
Well it would appear that there's a laundry list of updates you need to apply to your PC.
First stop would be to visit http://update.microsoft.com and apply the updates available... starting with XP Service Pack 2
That will require a few visits and some 300MB or more of updates.
Once you are done there try and get the latest forceware drivers for your video card as you're are from 2005.
Here's hoping that will fix most of the problems. One other major thing to consider is that your nVidia FX 5500 and 512MB RAM are right on the bottom end of machines that can run MxO.
You at least want to double your RAM to 1GB (that will give you the biggest performance increase.) Then you want to upgrade your video card to a 6xxx or 7xxx series video card. The 5xxx series cards only support PixelShader model 3 in it's most basic of implimentations. Unless you upgrade your video card you will not be able to use "overbright" at more than 1 or 2 frames per second.
"But I'm happy to play at low speeds" you say? Well the amount of time it takes for your video card and RAM to switch from in-game or Windows resolution to the resolution used by the Loading area will cause many many crashes... and you will end up resenting MxO (it happened to me).
You really need an upgrade if you want to run MxO with anything other than the lowest of settings.
Yeah your character is stuck. type /ccr ingame to bring up the petition submission site.
but you still need to apply all those updates