Some time ago I’ve had a problem with SVN on my VirtualBox guest Ubuntu machine. When the machine was hibernated (it’s state was saved – without shutting it down) there was a time synchronization issue.
When I checked out the SVN repository on the guest machine, I couldn’t see any actual changes or new files which I was 100% sure I committed before (because I did it from my host machine just a minute ago).
It occurred that the guest machine clock was not synchronized with the host’s. So, the guest clock stopped when it was suspended and, after resuming, the time just continued to flow. The time difference was so big that the SVN checkout was working on some weird past revisions (relative to the guest clock) instead of the actual ones.
It was all solved by installing the Guest Additions.