I noticed that using Windows 7 Tortoise SVN client often exits with an error message when trying to update/checkout files from the repository. The SVN checkout fails in that case. (And the system will perform a disk check at the next reboot)

This is caused by a bug in Windows 7 oplock file handling. Details can be found here.
Basically the error happens when another program tries to get a lock on the file while SVN is still doing the checkout – this can be Windows Indexer, Google Desktop, Backup Software, etc..

Microsoft released a hotfix for the issue – which should be included in Windows 7 SP1.
(Note that this hotfix replaces the previous KB 982927 hotfix the article above is linking to – and which doesn’t exist anymore)