I was getting this error. Tried starting with “-repair”, then renamed gw2.dat and ran with -repair, ran a disk check (ran 41/2 hours) not a single problem or sector bad. I noticed that the GW2.dat file had grown to over 15GB. My Anti-virus was set to “on access” which means that when a file is opened or read or written to it is scanned by the anti-virus software before the read or write is allowed to continue. I added the GW2.dat and exe to the exclusion list and so far the game has started up without errors 3 times in a row. I had the same problem at work were company live data files were in excess of 30 GB and the antivirus was set to check “on access” and the antivirus was failing which caused the application disk read or write to fail.