If you are using Maya 7 then follow this

1) Find the Maya.env file (...\Documents and Settings\User\My Documents\maya\7.0)

2) Open it with any text editor such as notepad

3) Add the following line to the end of the file:


MAYA_NON_POWER_TWO_OFF = 1

This will tell your graphics card to display the images differently.

4) Save and reset Maya.

If you are are on a later version of Maya then you can up the display quality of the image in the Attribute Editor to cure it and if that doesn't work sometimes changing the format of the image might solve it because .tiff can give funny results if the compression is of a certain type so convert it to .jpg