Can my company force me to take two weeks unpaid vacation?
Your employer has the right to furlough you for two weeks without pay during an established break, especially as s/he is doing the same thing for many other employees who have been on board for much longer than you apparently have. More notice would have been nice, of course, but the employer can still legally make this business decision.
Whenever someone says that they are "a salary employee," I have to assume that they mean "exempt employee" under the Fair Labor Standards Act. In some cases, that may be an incorrect assumption; but I have to work with what I am given.
So, if you are exempt under the FLSA and full work weeks are involved, the only problem that the employer may encounter would be if because of the two weeks without pay, your salary level as an exempt employee fell below the FLSA criteria set of $23,660 per year.
If that occurred, the employer could lose the right to classify your job as exempt and would be required to pay you on an hourly basis (including overtime for over 40 hours worked in a workweek if/when that occurred). For the change in classification to transpire, however, you would have to report your employer to the Department of Labor and their investigation of the circumstances would result in the final determination.
If partial workweeks were involved, my response would be different, by the way.