the instruction at "0x00a61507" referenced memory at "0x00a61507".

Test the RAM

If you can swap out the RAM with known good modules for testing first if you can't do that then test the machine with one RAM module at a time until you tested every module. Other wise run the the following RAM testers.
--------------------------------------------

NOTE IF THIS DOESN'T FIND ANYTHING WRONG WITH THE RAM THIS DOESN'T MEAN THE RAM IS GOOD you would need to swap out the RAM with known good modules for testing. However if it does find something wrong then chances are the RAM is bad.

DocMemory PC RAM
Diagnostic Software
http://www.simmtester.com/PAGE/products/doc/docinfo.asp

or

http://www.memtest86.com/ 

or

GoldMemory
http://www.goldmemory.cz/

Also check this thread

http://www-level3.experts-exchange.com/questions/20691130/URGENT-IE-6-DISABLED-BUGGED-Memory-could-not-be-read.html

Sunray

Try this resize you pagefile

Right clikc on My computer
Select Properties
Click the Advanced tab
Click the Advanced tab again
Click change
Set the max and min to the same size and probably set the size at about 520MB's and then experiment with the size if you encounterd problems by increasing it in size
 

Check for adware and sypware

spybot here
http://spybot.safer-networking.de/
Download
http://spybot.safer-networking.de/index.php?lang=en&page=download

AdAware
http://www.lavasoftusa.com/

Spycop:
http://www.spycop.com/

BHODemon and Hijack This and Browser Hijack Blaster
http://www.spywareinfo.com/downloads.php?cat=sp#det
BHODemon | Think of BHODemon as a guardian for your Internet browser: it protects you from unknown Browser Helper Objects (BHOs), by letting you enable/disable them individually. This program is my choice for BHO detection and is highly recommended.

Browser Hijack Blaster | Running silently in the background, Browser Hijack Blaster only springs into action when an attempt is made. It watches and protects the following items: IE Homepage, IE Default Page, IE Search Page, BHOs. Whenver one of the above items is changed, or a BHO is added, you are immediately provided with information on the item, along with the option to keep the change, or revert to your previous settings.

Hijack This | Written by a member of our support forums and based on our Hijacked! article, this program scans the locations in your computer system that may be modified by browser hijackers and fixes any problems found. An easy-to-understand tutorial is available at TomCoyote.org.

General and overall information about Spy/Adware
http://www.cexx.org/adware.htm

If it is just related to IE then

How to Reinstall or Repair Internet Explorer and Outlook Express in Windows XP
http://support.microsoft.com/default.aspx?scid=kb;en-us;318378

or

Start > Run rundll32.exe setupapi,InstallHinfSection DefaultInstall 132 C:\windows\inf\ie.inf

or

Right click on C:\windows\inf\ie.inf and select Install

>>the instruction at "0x00a61507" referenced memory at "0x00a61507". The memory could not be "read".<<
If the message is accurate, it's kind of interesting that the instruction seems to reference memory at it's own
location....

Cheers, Bjorn

Just done a check, the error message is correct