sorry to not post this to the nexus mod manager fourm, but im haveing this issue with NMM where when i try to activate 2 mods(grass on sterorids,skyrim grassifacation), a security alert comes up and says,"revocation information for the security certificate for this site is not available, do you want to proceed?" the 3 options are yes no and view certificate, what does this alert mean, should i uninstall these mods?.

Websites have "certificates" which autherize them as trusted and safe sites. Not having one doesn't mean the site isn't safe, just that its cirtificate is expired, doesnt have one, etc. Use common sense and know where you are downloading things from.

the site i downloaded the mods from was the skyrim nexus, witch i figure is a safe site, so should i just go ahead and proceed?.

Might try downloading them manually and see whats inside first. Viruses and whatnot can not run from inside a compressed archive.