An issue that initially came up in 2006 (Unable to compile #develop: access denied) "resurfaced" on our contributors mailing list because one of our developers ran into this very problem that McAfee blocks access to our Main\StartUp folder:

The problem and a workaround is described in McAfee VirusScan and the Startup folder. However, this developer doesn't have the administrative rights to change this setting of McAfee, so he asked whether we are going to rename the folder.

My take on this issue is that this is a bug in McAfee's software, because willy-nilly disabling anything that resides in a random folder called StartUp isn't a security feature.

Read the complete post at http://laputa.sharpdevelop.net/McAfeeAndSrcMainStartUp.aspx