Athlon 64 DEP and Skype


!Skype – Free Internet telephony that just works. I’ve found two applications so far that mysteriously crash on startup when they are running on the Athlon 64. In both cases, they are executing data code, a bad thing. One is Outlook and the other is Skype.
Here are the symptoms, it isn’t obvious from the error diagnostics:
# Windows XP SP2. This has the DEP (Data Execution Prevention) feature that uses the so called NX bit in the Athlon 64. What it means is that the processor itself detects when applications are executing in the data segment which is how most viruses get in.
# Athlon 64. You have an Athlon 64 and presumably also the new Pentium 4 that have the NX implemented.
# You go to Start/My Computer and right click and select Properties. You go to the Advanced tab, choose Settings and then Data Execution Prevention. The default is that it is only turned on for Windows itself, but I turn it on for all applications as it seems like good hygiene.
# What now happens is that certain applications like Skype and Outlook will now crash while executing, they don’t say it is because of the DEP turned on so it is trial and error.
# You can see if this is true by going to Start/My Computer/Properties/Advanced/Settings/Data Execution Prevention and browsing for the application in question and saying that it shouldn’t have this DEP turned on and then try to run it.
In both Outlook and Skype cases, the application crashes immediately, but I’m not sure that is true for everything.
Net, net, if you have crashes and you turned DEP on, then try turning it off.

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