You may need to set maxtransfersize in your backup statement.

http://support.microsoft.com/kb/904804

Do you use the third party tool to backup? Could you post your error?

If it is the case described by firasatahmed, add WITH INITI at the end of your command to overwrite the existing backup file.

Is the backup file in use?

With Windows XP SP2 or later, the answer is Yes.

MS SQL Server, I believe it is the same to other database servers, has a limit to run jobs from SQL Agent. If we schedule many jobs starting at the...

It depends on how you change your memory setting.

If you use GUI, you do not need to do anything more, such as restart SQL.

If you change it using scripts, you...

This is what I am not sure. My comment is only a kink of informal message.

SQL Profiler may help.

In SQL Server, we can modify the connection setup under the connection tab in the Properties dialog.

I cannot remember MySQL clearly. But MySQL should have the similar setting. You need...

The step 7, restore users and roles. You need to backup the users and roles before restoring your database, normally.

It does not seem to be a database server issue. Here is link. May it help.

http://www.mrexcel.com/archive2/38800/44953.htm

What version and SP do you use? In SQL 2000/SP4, we can see self-blocks quite ofen. It is called self-latch. It is fixed with new hotfixes.

You may consider replications (transaction for large database and snapshot for small database). However, transactional replication is harder to maintain.

You may also consider the differential backup/recovery.

The error message described clearly. The most often mistake is the owner of object is not dbo but under a user name. Please check.