I have been seeing that error since last May with version 10.0.2 all the way through 10.1.1 on roughly 30% of my laptops and have worked extensively with PGP technical support to get a fix. If I decrypt any of the systems affected, the Windows Delayed Write Failure errors go away immediately. In all instances, drive diagnostics have come back clean, no corrupted or damaged sectors. I even went as far as sending a new laptop that was just encrypted that received the Delayed Write errors almost immediately. Apparently there is/was an issue with the PGP software that monitored some critical PGP files and was supposed to replace them if they got moved or corrupted for any reason. The internal workings of the program was not replacing the moved/damaged files properly and would cause the Windows Delayed Write error. PGP has said they fixed it in rev 10.1.1 sp1 and later. I asked them if utilizing a Disk Defragmentation program could cause issues and they said YES......especially when their software was "broken" and not replacing the critical files when they were moved. We utilize Diskeeper as our automatic defragmentation software as a standard as it really keeps your system running as fast as possible from a file access perspective.
PS...the Delayed Write Failure errors were received on a wide variety of laptops and disk technologies.
Dell C640, D600, D610, D620, E6400, M4500, E6410
Hard drives: IDE 5400rpm, IDE 7200rpm, SATA 7200rpm, and even Solid State Drives (SSD)
OS : Windows XP sp3, Windows 7 Enterprise 32bit.
At the momemt I have uninstalled from the systems affected until I can validate in the lab that the issue has been resolved in 10.1.1 sp1 and later.
Hope this helps.