To find your current PST.. from in outlook there are a few ways (the steps are paraphrased for quick typing)..
1) go to Tools>accounts> data files and you'll see were your email is being delivered to...
2) go to folder view>right click on the Personal folder>properties>Advanced and you should see the location of your PST in the filename field. YOu can copy the path from here and paste it into an explorer window.. to get to the folder.
When you run ScanPST make sure you are running the most recent version... Its likely you may have different versions on your PST here and there. if you have Office 2007 it would have installed one too. what I do is search the hard drive for ScanPST and then run the one with the most recent date.

To delete the PIM.vol file you'll need to use a third party app because the built in file explorer will see it as a system file and won't let your delete it. I like Total Commander its free and very featured... also make sure you don't have any apps running that could be access the file, like the calendar or contacts app. use the task manager to kill any programs..
Mark

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Luck is where opportunity meets preparation.