pulldown menues not shown properly


I’m newbee to Blender (and 3D modelling).
Will need it to bake textures (sculpts) for Second Life so I downloaded Blender.
Problem is: The pulldown menues are not shown properly.
Some of them are displayed at the wrong position like the file menu from the main navigation bar to the top (1st pic).

or they are displayed as dark gray boxes instead of text


Installed Blender 2.44 for Windows twice - but every time the same error.
Also the highlighted menu item is not where the mouse cursor points to but some lines above or below - can be changed by the mouse wheel but than either the wrong submenue pulls up or none (p.e. when trying to select “Import” from the script window)

Graphic card ATI Radeon 9000, Windows XP pro

Could someone kindly assist me?

Thank you in advance :wink:

Brgds from Salzburg