Sorry I forgot to mention that I am using .NET Framework version 1.1 service
pack 1. The problem happens on both Windows 2000 Server and Windows Server
2003 machines.

I found your post when I was encountering the same problem. And did not see a resolution for it.

Here is what happened to me.

After days of scouring multiples times through every field/object that was being sierielized, I finally found one that had some very unusual data.  And there was a lot of it, it almost looked like what I used to see in old C code for an unterminated string. Of course I have been told that that is impossible for .Net code, it still looked that way to me.

Anyway the field in question was being populated by a call to the database for a single date field from a table. I am using an Oracle 8i db, the select was "SELECT TO_CHAR(MAX(DB_DATE_FIELD), 'YYYYMMDDHH24MISS') AS VAL FROM TABLE_OF_DATES".  The tricky part was that it did not always return the "garbage", somtimes it was a NULL, sometimes it was real data. I tried the SQL repeatedly outside of the program, sqlplus, and every time it returned me the maximum date.

I played around with the select inside the program and found that the table had null values in some of the rows for the date. This should not have mattered but I was at my wits end, so added "WHERE DB_DATE_FIELD IS NOT NULL" to the SQL and TA DA !!! I got a good value.  I have been watching it now for the past 2 days and so far so good.

My suggestion to you is to create a method thats dumps the object you are serializing to a debug/log file that you can easily access. Also put a try...catch around your serialize method so you can match up the dumped object with the attempt to serialize. At least that way you know what data is being processed when the error occurs. After a few tiems a pattern my show up.

I hope this helps you in some way. If you found a differnt cause or solution please post back.