How to fix .NET installer failure?

[Pat Furrie]

I've been trying to install an update to a 3rd party program, and been
having no luck. After some investigation, it looks as though the program
uses .NET installer, so I thought I'd check the Windows Update site for any
updates, which there is -- .NET framework 1.1. I've attempted to install
the .NET 1.1 package several times, and everytime it fails. Finally, I
downloaded the update file from Microsoft's download site and tried it that
way. During the installation, I get an error message that looks just like
the error message I get from the 3rd party program I was originally trying
to update:

Microsoft .NET Framework 1.1 Setup
The system cannot open the device or file specified.
<Retry> <Cancel>

Retry gets me nowhere. If I click Cancel, I get another error message that
also looks a lot like the error I get from the 3rd party installer:

Microsoft .NET Framework 1.1 Setup
Internal Error 2755. 110,
C:\DOCUME~1\Pat\LOCALS~1\Temp\IXP000.TMP\netfx.msi
<OK>

A search on Microsoft's web site for "cannot open the device or file
specified" comes up with no hits.

What might be causing this error?

How can I get the .NET Framework installed?

Thanks much.

Pat Furrie