A computer registry is a part of your computer that maintains
important data about many of its regular operations. However, if it
becomes corrupted with too many problems, it can seriously impede
your computer's performance.
What is a Computer Registry?
Your registry remembers important information about your users such
as their preferences and profiles. It communicates with many or most
of your applications, telling your operating system how to best
interact with them. It is working all the time even if you never once
open it up to view it.
Your computer maintains your registry automatically via multiple
daily reads and writes of data. This means that your registry is
actually being changed constantly by your computer in its effort to
stay current on your usage patterns.
What Kinds of Problems Can Occur?
Registries can and do become corrupt over time, however. Regardless
of how prudently and carefully you operate your computer - such as
taking important steps like running anti-virus and anti-spyware scans
regularly - your registry will still become full of problems over
time. For example, uninstalling software and deleting certain
application or file can corrupt your registry. Even if you rarely
touch your files or move them around, your registry will still be
subject to problems through daily computer use....

Registry Repair: http://groups.yahoo.com/group/regrepairsbv