From 32KB to 325KB? It seems to me that you have not emptied your Temporary internet files before viewing the .dat file again?
Try emtpying the temp files and history then check to see if the size of index.dat has changed.
With regards to the other issue (another application is accessing it.), Open task manager to view if wordpad.exe is in the list. If wordpad.exe is listed, highlight it then select stop or end process or shutdown task.
-Donna
Something new. Per Donna's advice, I set Notepad to open my dat file and it worked. File had only 32 k in it. Now it has 325k and when I try to open it says it is too big and do I want to use Word Pad and I say yes. Then it gives me the message that it can't be opened because another application is accessing it. I don't have anything open. I restarted and got the same thing.

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