Database Server Will Not Expand Mdf Or Ndf Files

Has anyone had an issue with SQL Server not being able to expand
against a RAID 5 file system? My current configuration is that the
server is started and stopped using the local system account. I have
only one database (besides the master, model,etc)on the server. What
has happend to me several times is that the primary database in
question try's to expand the main datafile for the database (.mdf). I
setup the database to not expand automatically initially so that I can
be sure that we have enough file system space. Becuase of problems with
the application I decided to automatically expand. The other day the
developers came to me indicating that the databse was full and needed
to be expanded. Knowing that the database was in automatic expanding
more I was surprise to hear this. I went into EM and attempted to
expand first the log and it would not indicating that it there was an
issue in attempting to do so. I have never heard of a database not
being able to expand. I ran DBCC's, etc and it came up clean. I tried
to back the database up to disk and it would not backup. I finally had
to rename the datbase and rebuild it using DTS and scripts. I thought
I had fixed it only to find out today that it (again) won't expand. I
renamed the datbase and then tried taking an older backup file and
restore it and it would not restore. This problem seems to be related
to the file system but how I do not know.

So, I am ready to run rebuild master but I have sone this before only
to have this come back on me. I am at a complete loss. In the past I
have had to rebuild the entire server and database from scratch. The
only problem is that this has been done 3 times now with no complete
solution or explaination. If any of you have seen this type of
behavior and know whats going on please, please let me know what you
think the case and solution is!