Data Execution Error on opening Windows Explorer

This is a problem that I've not seen before, but was able to fix thanks to Arie's article on "Trouble Shooting Windows Explorer Errors ". As the problem involved a XP Pro SP2 PC and a very popular download, I thought it worth posting the problem and the fix.

Problem
User reported being unable to open Windows Explorer. On opening explorer, an error appeared: a report from the Data Execution Prevention system, saying that explorer.exe was trying to access a protected area of memory.

The PC had been working fine last week. Only change reported by the user was installing Real player.

My first thought was there was a trojan that had hijacked Windows Explorer. Anti-Virus was up to date and hadn't detected anything so I installed and ran a couple of anti-spyware apps (a couple of the ones recommended in PeteC's article "Keep your Computer free from Viruses, Trojans, Spyware and other Malware "). All they picked up was the usual marketing cookies.

Solution
Real Audio Player then moved to the top of the list of likely culprits. I downloaded and ran ShelExView (as described in Arie's article). This showed that there was an extension "Browser Helper Class ", description "Real Download ". I used SheExView to disable this Explorer Extension and this fixed the problem.