missing file in distro

[John R. Sowden]

I have seen a file missing message about 30 times per boot up in the log 
file that scrolls quickly by as I log in.  The distro us xubuntu 13.10.  
The file is systemd udevd.  I know those are 2 words, but it scrolls 
very fast and I can see it only because it is repeated as it retries and 
it pauses for a bit.

What do I do?  Can I reinstall the OS on top of the existing system, or 
might I write over config files, data, etc.

John