Recently there has been some confusion regarding ProClarity Web Professional and 64-bit Internet Explorer. ProClarity Web Professional and the prerequisite Download Manager are both 32-bit ActiveX controls which will never run in 64-bit IE. More information here, and here. The workaround is to use the 32-bit version of IE which is included with 64-bit Windows.
So, look at the requirements.pdf document for OS support and to the forums and blog for solutions to known issues. Remember that ProClarity Web Professional will always need 32-bit IE.