Adobe recently released a new 64-bit Windows version of Acrobat.
If you have a PitStop Pro please note that currently, all windows versions of PitStop are not compatible with the 64 version of Acrobat. Until now both Acrobat and PitStop Pro on Windows have been available only in 32-bit.
The Adobe Acrobat installer will check the Acrobat plugins that you are using, and if it finds any 32-bit versions it will not install the new 64-bit version of Acrobat. It will install the 32-bit version instead.
Enfocus is working on a new version of PitStop that will support Windows 64-bit. This update is expected in April and should be available to beta test around the end of February. If you would like to be involved in the Beta, please contact the PitStop product manager, Andrew Bailes-Collins.