Sorry to repost such an old thread, but in case anyone else is having this problem in the future I do want to give an update.
The TrackIR.dll file was continually removed from the v1.4.2 update by my AntiVirus software during download. In order to complete the download successfully, I had to:
1). Shut down my AntiVirus software during the download
2). Run the install program
3). Go into Norton Antivirus and exclude the TrackIR.dll file from the scan list
Once these steps were done, the update functioned correctly. However, if they were not done in order, the AntiVirus software would find and remove the file and the update would not work. The file would then have to be re-downloaded, which was not a comfortable experience given the file size and not having the AntiVirus software running.
But, in the end everything worked!