Just recently bought T:DS and I am having a problem with crossing over map
checkpoints. Still new into the game so I don't know if this will continue.
When I crossover through a checkpoint the game exits to the desktop and then
starts again as if I had just started the game up. I ...

Hpws the mission level you were working on coming along?

 Been all over the house on Stiff Competition fm and cannot find any keys.
Anyone assist?

at least until earlier today, the soundtrack for T:DS was available for
download at the following address:
http://files.filefront.com/Thief_Deadly_Shadows_Soundtrackzip/;4712193;;/fileinf
o.html
The website of news magazine "Der Spiegel" reported about this. However,

If the rest of this FM is half as good as the intro, it's a winner!
http://www.thiefmissions.com/info.cgi?m=Snobs2

This one is a must-play.  It's got the lot!  Get it from Cheap Thief
Missions here:
http://thiefmissions.com/info.cgi?m=SepulchreOfTheSinistral