I'm familiar with programs which run NET 1.1 to NET 4.. Which version did you attempt to install? When the computer asked for NET Framework to be installed, it should have told you which version was needed. The are links to the "full" NET Framework installer, but the correct version would be needed. For example, the links below include 2.0, 3.0, 3.5, and 4.0. They do not include version 1.1 which may, may not be needed.

NET Framework 2.0, 3.0, and 3.5 SP1 for WinXP
http://www.microsoft.com/en-us/download/details.aspx?id=25150

NET Framework 4.0 Client Profile and 4.0 full (Install Client Profile First)
http://www.microsoft.com/en-us/download/details.aspx?id=24872

http://www.microsoft.com/en-us/download/details.aspx?id=17718

It seems strange that simply plugging in the memory stick would require .NET... Does the memory stick contain special software such as antivirus or "vault" types of software? A standard, empty flash drive shouldn't need such.

Hope this helps and let us know more.

Grif