New chapter will not load
 

After the cut scene at the end of chapter 4 I get dumped to the challenge room menu. I un-installed Necrovision from Steam and re-installed it. Now I can not get past chapter 1. Chapter 2 will not load. Also there is no patch for the downloadable game. My Kaspersky antivirus is turned off when I play and Necrovision is an exception in my Windows firewall list so no problems there.
Has anyone else had this issue?
Any ideas and feedback will be appreciated.
Thanks.

PS. my system is up to date.
Specs: XP Pro sp3, Quad QX6850, Asus Maximus Formula, 2gig Dominator 1066, Sapphire 4870x2,
Am I missing any specs needed for a diagnosis? Please let me know.
Thanks.

(maybe my answer is completly off the mark, but...)
If you start a level through the challenge menu, at the end of that level you return to the challenge menu. YOU CANNOT use the challenge menu to resume your progress in the campaign.
However, when playing a level in challenge mode, the game makes savegames aswell. Perhaps when you loaded your game you picked a save made in challenge mode instead of a normal save.