Javascript conflict with Webform file components and fb_social in IE

When submitting a Webform form with a file attach component on a page that also has fb_social's like plugin installed a Javascript error is displayed. You can test in IE at http://www.acton.org/webform/student-internship-application (all you have to do is hit submit and the JS error will present itself). There seems to be no problem with Webforms that do not have a 'file' component.

I have remedied it and narrowed it down to fb_social by removing the fb_social plugin from Webform node types and having it disappear, but I now need this functionality again.

Errors:

Webpage error details

User Agent: Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.1; Win64; x64; Trident/4.0; .NET CLR 2.0.50727; SLCC2; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0; MDDS; .NET4.0C)
Timestamp: Tue, 19 Apr 2011 18:29:36 UTC


Message: Exception thrown and not caught
Line: 5
Char: 399
Code: 0
URI: http://www.acton.org/sites/v4.acton.org/files/js/js_72da4b7c6c6d4eff15fb672c4b4756e6.jsmin.js


Message: Object doesn't support this property or method
Line: 48
Char: 339
Code: 0
URI: http://www.acton.org/sites/v4.acton.org/files/js/js_72da4b7c6c6d4eff15fb672c4b4756e6.jsmin.js