Saving to SharePoint works only half the time for Windows 7 Users--all the time for Windows XP users

We have a SharePoint 2010 Environment with hardware load balancing, 2 WFEs, 2 Apps Servers and 1 SQL Server. This was built in October 2013. Office Integration and Saving back to SharePoint works all of the time for users on XP. It works sporadically for users on Windows 7. When Windows 7 users do the following:

• Opening an Office Document from computer and saving it to SharePoint


• Within a Document Library, using Save As from an opened document


• When selecting in a Document Library from the Document Tab> “New” and then the desired content type


• Send> Save to SharePoint from within Office Document

They may either be brought to the SharePoint library (correct) or to My Documents (incorrect).

In the case of number 1 (Opening an Office Document from computer and saving it to SharePoint)--using Save and Send will sometimes open the SharePoint library and sometimes open My Documents.

Our URL is https://CompanyName.domainname.com/Sites/SiteCollectionName

The intermediary "Sites" is actually a blank path.

When My Documents is opened I've noted with Fiddler (a web debugger) that we get a 404 on sites:

Could this be the issue?