Background Noise, I have the same problem with JPEGs as well. This has me stumped as the problem only seems to have arisen recently.
Workaround solution was - Open TIFF in Photoshop. Resize etc then save as PDF. Open PDF, and just do a cut and paste of requried drawing back into master Word document. Voila! After days of cursing and swearing my boss as well as Mrs IJ, both of who by their own admission are the least computer savvy came up witht the suggestion.