Investigate if there is a problem opening files with asynchronous support from read-only volumes.

[alphaleonis]

Created from #105

File.Open needs to create an FileStream with the isAsync-flag set to "true". But I have problems with overlapped-I/O and read-only volumes (e.g. Shadow-Copies).

File.Open results in error-messages "media is read-only", even if i open the file only read. The error disappears, if i don't use overlapped i/o.

Investigate whether we can reproduce this and if so, update this to a bug and find a solution to fix it in that case.

Possibly relevant links: -http://www.getcodesamples.com/src/A1C575BD/3FA4157B -http://www.beefycode.com/post/Using-Overlapped-IO-from-Managed-Code.aspx