Why do you need FolderGuard if you are already using TrueCrypt? I don't know how FolderGuard works but if it messes with the boot sector (like TrueCrypt's full-disk encryption does) then you may have had a conflict there. TrueCrypt (and possibly FolderGuard if it works in a similar fashion) makes the disk unreadable to any other software; you MUST use the tool for that encryption program, or one that's fully compatible, in order to open it.