I'm on a PC and I don't have QT pro, just Quicktime player, the download freebe.
It's still probably a QT issue though, it's stolen the file association.
If you have Windows XP go:
Control Panel>Folder Options>File Types
Select the file extension .tif from the big list, you'll probably see Quicktime associated with this extension, click on Change and choose Photoshop instead.
In Vista it's different:
Method #1 (on the fly):
1. Right-click a file of the type you want to change, and select Properties.
2. In the General tab, click the Change button.
3. Choose a program from the list, or click Browse to select an .EXE file on your hard disk.
Method #2 (view a list of file types):
1. Open Control Panel.
2. In Control Panel Home, click Programs, and then click Make a file type always open in a specific program.
Or, in the Classic View, open Default Programs and then click Associate a file type or protocol with a program.
3. Highlight a file type in the list and click Change Program.