Hey, I installed the Shivering isles and Knights of the Nine at the very start.....as soon as I installed Oblivion. As I had Frostcrag Spire, I started creating spell immediately and all was fine but after some time I dont know why but whenever I created a spell then I exited Oblivion and played again later, I could not find that spell. Further more I checked and the money that the spell costs me, disappears. I managed to ignore this by buying most of my spells.

But lately I started enchanting armor using sigil stones and the same happened! When I exited the game and played later, the enchanted items disappeared and so did the used sigil stones!

Any ideas please?

Not a hardware issue. learning how to use http://tesnexus.com/downloads/file.php?id=2097 program would probably help you out. i'm guessing this is an issue with your load order which results in conflicts (say if you load your unofficial shivering isles patch before you actually load shivering isles things get messed up as a good example). some mods are better at the bottom of the load order.

It's the http://www.uesp.net/wiki/Shivering:Reference_Bug. You need the latest patch.