Windows 7: w7 updates cause OS to fail to load

I am running Windows 7 home premium 32 bit on a Dell M170 laptop and have had problems with Windows update that have required me to reinstall Windows 7 twice. The last time (4 days ago) has left me very gun shy about installing any updates although on my Desktop running Windows 7 Enterprise 64 bit I have had no problems.
A brief summary of the events is as follows:



1) Installed Windows 7 Home premium 32 bit OEM on dell M170 laptop. on a hard drive with 2 partitions (XP and Windows 7) in early January
2) Ran successfully for about 2 months and after installing updates I got the repair menu which was unsuccessful as was system restore.
3) Reformatted hard drive and eliminated XP partition, and installed Windows 7.
4) Installation on drive (no partitions initially) created a hidden partition (100 Mb) and main OS partition.
5) Removed Avast anti virus and installed Microsoft Security Essentials
about 2 months ago
6)Updates installed about 10 days ago and after first reboot get message saying windows is not genuine.
7) Reactivated successfully but on next boot Microsoft Security Essentials states that Windows 7 is not genuine and will cease to work after 30 days. Reactivated Microsoft Security Essentials.
8) Next boot without making ANY other changes causes OS to fail to load.
9) Repair and attempted System restore unsuccessful as was attempt to reinstall an old image using Casper.
10) First installation of Windows 7 unsuccessful (no boot)
11) Deleted hidden partition and reformat main partition and installation now successful.
12) Running Avast & Malwarebytes(active) instead of Microsoft security essentials & Malwarebytes(active)

As you may guess this has been a frustrating experience and has left me very suspicious about installing Windows updates and about running Microsoft Security Essentials.
Any advice or comments would be appreciated.