Trying to delete a directory recursively with rm -Force -Recurse somedirectory, I get several "The directory is not empty" errors. If I retry the same command, it succeeds.

Example:

PS I:\Documents and Settings\m\My Documents\prg\net> rm -Force -Recurse .\FileHelpers
Remove-Item : Cannot remove item I:\Documents and Settings\m\My Documents\prg\net\FileHelpers\FileHelpers.Tests\Data\RunTime\_svn: The directory is not empty.
At line:1 char:3
+ rm <<<<  -Force -Recurse .\FileHelpers
    + CategoryInfo          : WriteError: (_svn:DirectoryInfo) [Remove-Item], IOException
    + FullyQualifiedErrorId : RemoveFileSystemItemIOError,Microsoft.PowerShell.Commands.RemoveItemCommand
Remove-Item : Cannot remove item I:\Documents and Settings\m\My Documents\prg\net\FileHelpers\FileHelpers.Tests\Data\RunTime: The directory is not empty.
At line:1 char:3
+ rm <<<<  -Force -Recurse .\FileHelpers
    + CategoryInfo          : WriteError: (RunTime:DirectoryInfo) [Remove-Item], IOException
    + FullyQualifiedErrorId : RemoveFileSystemItemIOError,Microsoft.PowerShell.Commands.RemoveItemCommand
Remove-Item : Cannot remove item I:\Documents and Settings\m\My Documents\prg\net\FileHelpers\FileHelpers.Tests\Data: The directory is not empty.
At line:1 char:3
+ rm <<<<  -Force -Recurse .\FileHelpers
    + CategoryInfo          : WriteError: (Data:DirectoryInfo) [Remove-Item], IOException
    + FullyQualifiedErrorId : RemoveFileSystemItemIOError,Microsoft.PowerShell.Commands.RemoveItemCommand
Remove-Item : Cannot remove item I:\Documents and Settings\m\My Documents\prg\net\FileHelpers\FileHelpers.Tests: The directory is not empty.
At line:1 char:3
+ rm <<<<  -Force -Recurse .\FileHelpers
    + CategoryInfo          : WriteError: (FileHelpers.Tests:DirectoryInfo) [Remove-Item], IOException
    + FullyQualifiedErrorId : RemoveFileSystemItemIOError,Microsoft.PowerShell.Commands.RemoveItemCommand
Remove-Item : Cannot remove item I:\Documents and Settings\m\My Documents\prg\net\FileHelpers\Libs\nunit\_svn: The directory is not empty.
At line:1 char:3
+ rm <<<<  -Force -Recurse .\FileHelpers
    + CategoryInfo          : WriteError: (_svn:DirectoryInfo) [Remove-Item], IOException
    + FullyQualifiedErrorId : RemoveFileSystemItemIOError,Microsoft.PowerShell.Commands.RemoveItemCommand
Remove-Item : Cannot remove item I:\Documents and Settings\m\My Documents\prg\net\FileHelpers\Libs\nunit: The directory is not empty.
At line:1 char:3
+ rm <<<<  -Force -Recurse .\FileHelpers
    + CategoryInfo          : WriteError: (nunit:DirectoryInfo) [Remove-Item], IOException
    + FullyQualifiedErrorId : RemoveFileSystemItemIOError,Microsoft.PowerShell.Commands.RemoveItemCommand
Remove-Item : Cannot remove item I:\Documents and Settings\m\My Documents\prg\net\FileHelpers\Libs: The directory is not empty.
At line:1 char:3
+ rm <<<<  -Force -Recurse .\FileHelpers
    + CategoryInfo          : WriteError: (Libs:DirectoryInfo) [Remove-Item], IOException
    + FullyQualifiedErrorId : RemoveFileSystemItemIOError,Microsoft.PowerShell.Commands.RemoveItemCommand
Remove-Item : Cannot remove item I:\Documents and Settings\m\My Documents\prg\net\FileHelpers: The directory is not empty.
At line:1 char:3
+ rm <<<<  -Force -Recurse .\FileHelpers
    + CategoryInfo          : WriteError: (I:\Documents an...net\FileHelpers:DirectoryInfo) [Remove-Item], IOException
    + FullyQualifiedErrorId : RemoveFileSystemItemIOError,Microsoft.PowerShell.Commands.RemoveItemCommand
PS I:\Documents and Settings\m\My Documents\prg\net> rm -Force -Recurse .\FileHelpers
PS I:\Documents and Settings\m\My Documents\prg\net>

Of course, this doesn't happen always. Also, it doesn't happen only with _svn directories, and I don't have TortoiseSVN cache or anything like that so nothing is blocking the directory.

Any ideas?