You must not post in all caps!
Right Click on the TIFF file, select open with, choose the program used for last 4 years.
Seems you are mentioning "Windows Picture and Fax Viewer"
Don't forget to check the "Always Use the selected program for opening this type of file" box
I am suggesting you to download & install the freeware IRFANVIEW! Very effective & useful tool!
http://www.irfanview.com/
These guides may help you
http://support.microsoft.com/kb/329270
http://support.microsoft.com/kb/921048