Hello Nirva,
The more I think about this, the more I believe it must be because of wrong VS keybindings assignment. Did you have ViEmu installed when you installed VS2008? That may be the cause. Can you go to Tools|Options|ViEmu->Keyboard, copy the contents of both lists ('Saved keybindings' and 'Current clashing keybindings') and paste them here?
If I am right, these would be the steps to fix the problem:
1) Go to Tools|'Import and export settings', choose 'Reset all settings', decide whether to save a backup or not, choose your preferred base config (Visual C++, General, etc...) and click Finish to reset all settings
Also if I am right, Enter should now work normally. The only remaining thing to fix now would be to process clashing keybindings such as Ctrl-F, so that they it does a page down instead of bringing up the Find dialog. These would be the steps to fix this:
2) Go to Tools|Options|ViEmu and click 'Keyboard...'.
3) Click "Forget" under the left-hand-side list. Answer yes to the confirmation dialog.
Now, the left-hand-side list should be empty, and all keybindings should be active on the right hand side. Final step:
4) Click "Save and remove" under the right-hand-side list (answer yes to the confirmation).
This should leave the right-hand-side list empty, having removed the offending keybindings, and all of them should be on the left-hand-side list (removed, but remembered by ViEmu to be restored when ViEmu is deactivated).
Let me know whether this fixes the issue.