windows explorer / DES - infection-free PC slowed down to mcrawl

Well I don't know where to start, so I shall just list the problems as concisely as possible.

SYSTEM
WS: Dell Intel Core 2 quad CPU - 4GB RAM
OS: Windows Vista Business
Protection: McAfee 12.8.0.0 / Ad-Aware 10.5.2.4379

ISSUES

Windows Explorer continually closes programs, folders, files & browsers. Common excuses:-

1. Data Execution Prevention – Microsoft Windows. To help protect your computer, Windows has closed this program. (What? ....with Notepad?)
2. A script on this page may be busy, or it may have stopped responding. You can stop the script now, or you can continue to see if the script will complete. ​

These issues arise both live and in safe mode.

Operations most commonly affected

Thunderbird (takes 5-10 minutes to open/search, cannot access work emails)
MS Word
MS Notepad
McAfee Security Centre
Control Panel
Seamonkey/Firefox (seems to open a double frame & completely freezes)
Google Chrome
Internet Explorer
Windows Explorer itself (opening & closing folders & files​

Solutions tried

McAfee full scan
Ad-Aware full scan
Microsoft Safety Scanner
All reported no viruses, spyware, and other potentially unwanted software were detected.
also... Autoruns ​

Below are examples of the error reports. Can anyone please advise me what is causing my PC to slow almost to a standstill?

Thank you & regards
Will Golden


Examples of error reports

Description
Stopped working
Problem signature
Problem Event Name: APPCRASH
Application Name: NOTEPAD.EXE
Application Version: 6.0.6001.18000
Application Timestamp: 47918ea2
Fault Module Name: unknown
Fault Module Version: 0.0.0.0
Fault Module Timestamp: 00000000
Exception Code: c0000005
Exception Offset: 73f374b2
OS Version: 6.0.6002.2.2.0.256.6
Locale ID: 2057

Description
A problem caused this program to stop interacting with Windows.
Problem signature
Problem Event Name: AppHangB1
Application Name: AdAware.exe
Application Version: 10.5.2.4379
Application Timestamp: 5146eb72
Hang Signature: 4edf
Hang Type: 517
OS Version: 6.0.6002.2.2.0.256.6
Locale ID: 2057
Additional Hang Signature 1: 6e9d41a7175922b9f2c0d5befe2a8d51
Additional Hang Signature 2: 2456
Additional Hang Signature 3: f2932d6fb79dcb39c1944261b7c2b339
Additional Hang Signature 4: 4edf
Additional Hang Signature 5: 6e9d41a7175922b9f2c0d5befe2a8d51
Additional Hang Signature 6: 2456
Additional Hang Signature 7: f2932d6fb79dcb39c1944261b7c2b339

Description
A problem caused this program to stop interacting with Windows.
Problem signature
Problem Event Name: AppHangXProcB1
Application Name: WINWORD.EXE
Application Version: 12.0.6683.5001
Application Timestamp: 51fd43eb
Hang Signature: 361b
Hang Type: 32
Waiting on Application Name: explorer.exe
Waiting on Application Version: 6.0.6002.18005
OS Version: 6.0.6002.2.2.0.256.6
Locale ID: 2057
Additional Hang Signature 1: c6032e6016c5ec49a7ad935c9f4d8f48
Additional Hang Signature 2: 6ad9
Additional Hang Signature 3: 98b24039123f31bf0ecac71c893fd13b
Additional Hang Signature 4: 361b
Additional Hang Signature 5: c6032e6016c5ec49a7ad935c9f4d8f48
Additional Hang Signature 6: 6ad9
Additional Hang Signature 7: 98b24039123f31bf0ecac71c893fd13b

Description
A problem caused this program to stop interacting with Windows.
Problem signature
Problem Event Name: AppHangB1
Application Name: Explorer.EXE
Application Version: 6.0.6002.18005
Application Timestamp: 49e01da5
Hang Signature: 45f0
Hang Type: 16897
OS Version: 6.0.6002.2.2.0.256.6
Locale ID: 2057
Additional Hang Signature 1: 69e6dc81570dab3c2d1774b21d0e480d
Additional Hang Signature 2: d885
Additional Hang Signature 3: 0124c845670659354d2dce55bbaa1705
Additional Hang Signature 4: 9117
Additional Hang Signature 5: f7eeed9a7b6efec322de0c39516c7145
Additional Hang Signature 6: 27b9
Additional Hang Signature 7: b5a8ea57d339f6eda371ba1c0a484eb7
Extra information about the problem
Bucket ID: 559087144

 

Greetings, willgolden.

If you're seeing these symptoms in Safe Mode then something's definitely going on with Windows. Do you have a Windows Vista installation disk? Regardless if you have a disk or not, I recommend that you run a System File Check (SFC) and try to clear up any operating system issues - it would just be better if you have a Vista disk in case the SFC needs to grab some files.