Why I cannot open the pdf file within Internet Explorer 64-bit version?
Internet Explorer 64-bit and 32-bit versions are both bundled with Windows XP 64-bit systems. Adobe Acrobat 7.0 can open PDF files inside the browser window only if you use the 32-bit version of Internet Explorer. Acrobat installs a 32-bit ActiveX control (pdf.ocx) that enables Acrobat to open PDF files within Internet Explorer; the 64-bit version of Internet Explorer 6 does not support 32-bit ActiveX controls. If the browser is Internet Explorer 64-bit, then PDF files can only be opened in the stand-alone Acrobat application after you saved it, and not inside the browser window.