I just recently ran into a new error that is confusing me quite a bit.  I took a 3 week vacation and when I came back, I get this error, but ONLY on my local machine (never happened before I left).  The code runs fine on the production box.  Also, keep in mind that we do constant updates where I work, so that is what I am suspecting caused the problem.  Here is the error: 

Could not load file or assembly 'System.Transactions, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' or one of its dependencies. The module was expected to contain an assembly manifest.

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.BadImageFormatException: Could not load file or assembly 'System.Transactions, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' or one of its dependencies. The module was expected to contain an assembly manifest.

Source Error:

Line 477:        SqlCommand cmdFillData = new SqlCommand(strFillData, conExists);

Line 478:
Line 479:        conExists.Open();
Line 480:
Line 481: 

One of my coworkers said that this could be caused by a machine.config file being altered, but my local machine never was.  Any ideas?  Thank you very much, and please let me know if there is anything I can clarify.