Sitecore editor hassles

Recently I experienced an extremely annoying error which occurred
within the sitecore editor:

"Description: An unhandled exception occurred during the execution of
the current web request. Please review the stack trace for more
information about the error and where it originated in the code.

Exception Details: System.IO.FileNotFoundException: no segments* file
found in Sitecore.Data.Indexing.FSDirectory@D:\Inet\Websites\Development\Website\indexes\master\system:
files:
"

Just a plain .NET Exception page... What caused the error?

/*TODO: description LUCENE, stackoverflow,*/

FIX:
Goto sitecore "control panel", choose "Database" and "Rebuild the
Search Index" and reload sitecore. Done :)