Internet Explorer Installation Problem

I have IE version 4.0 and am trying to upgrade to IE 5.0 or 5.5. I go to
the Microsoft site and am able to download the setup program for 5.0 or
5.5. After this I try to run the setup program but either cannot complete
the installation or if complete the installation  I am then unable to find
the new IE 5  anywhere. The existing IE 4.0 does not get upgraded and stays
the same

I go to C/My Downloads and click on the setup program ie501.

  The following problem occur when I click on the setup program and try to
complete the installation. 2 signs appear halfway through installation:

First this sign pops up 3/4 through installation when it is trying to
download the 128 bit encryption component:
"Windows Update: Internet Explorer and Tools
Setup was unable to download the required components. Please make sure you
are connected to Internet or try to run setup later"

After I click OK I am taken to Download File Information; Select Best
Location; Start Download. I click start download and download completes.

Then setup continues but then this sign pops up:
"Windows Update Setup is already running. You cannot open a second instance
of the program"

I have tried this many times on different days with same result. This is
happening since I switched from Dial Up to Cable Access.

I have tried to remove IE 4.0 first but cannot do this because backup file
are missing and you cannot uninstall IE 4.0 without back up files.

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