OK... some things to report(remember, running Vista Home Premium w/ latest SP1): 1. The context menu had really been flummoxed-- as well entries like Run as Admin were gone, even for .msi... HOWEVER-- the context menu was unchanged / undamaged for SHORTCUTS of extensions in question: exe / zip / msi / etc. BUTTTT..... selecting those commands ie running a shortcut of an msi file as Admin, etc. resulted in "no action occurring"... i see this is as a frequently-mentioned problem in Vista web-wide BTW. 2. I fixed everything(after trying numerous expected fixes-- registry(added Run as Admin to context of each extension...to no avail...etc.), uninstall/reinstall, etc.-- here's how: A. Simultaneously uninstalled: 7-z, 7zip, AlZip, IzArc, PeaZip, TugZip, Universal Extractor (sorry but have very little disposable time these days to post here, let alone experiment one app at a time). B. Removed from context menu all leftover entries re those apps(used the module from Glary Utilities) EXCEPT for those of Universal Extractor, 7zip & ZipInstaller. C. Re-installed latest versions of(with all file associations DEselected BUT all context menu entries selected in all of them): Universal Extractor(1.6 BETA), 7zip, IzArc... plus re-enabled context option in ZipInstaller. Everything back to normal(even things like Run as Admin) except: D. IzArc context entries will not appear in context menu. E. Having not associated .zip with any particular app, double-clicking such a file opens up Universal Extractor. 4. Conclusion(s)???? Draw your own.... it was either: F. One of the permanently-removed apps was the culprit.. especially since i now seem to remember some such context issues on other systems from years ago: win98, winXP. ORRRRR: G. The sheer number of context entries(I run at high-resolution on a large monitor, and even then the context menu scrolled off the top and bottom). BTW, yes, was still able to access any entry thru the scroll arrows. H. LAST BUT NOT LEAST: Universal Extractor is to be held blameless here. Good Luck all.