A Google search (Windows Journal Viewer Acrobat) suggests:
Uninstall both programs.
Reinstall Acrobat
Reinstall Journal Viewer if you need it, which I suspect you don't.

Background information)(From:
http://www.adobe.com/support/techdocs/31e16.htm)


Windows Journal Viewer is an application that enables you to view files that
were created in Windows Journal Viewer on a Tablet PC. Acrobat, and other
programs, share components with Windows Journal Viewer. If Windows registry
entries for Windows Journal Viewer are corrupt, the Windows Installer repair
process for Windows Journal Viewer tries to repair the corrupted registry
entries when you try to start Acrobat.
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Hi I have windows XP  processor AMD Athlon 64 I have downloaded Adobe Reader
6.0  but when I try to use it it trys to install and then tells me that it
can't because I don't have Windows Journal Viewer, I went to Microsoft and
downloaded this, but my computer refused to install it, would not tell me
why.  Is their anyway I can get Adobe Reader installed without this journal
viewer.

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