Security certificate error

Been having gmail problem, hope some one can help. cannot access unless I go through 'unsecure site' No other sites affected, did have a hiccup with Google few weeks back, but that has fixed, but since when I try to access gmail, get this
'Security Warning'
Current site http://mail.google.com
Trusted site:https://www.google.com
yes or no ( in check boxes )

If I check yes I get redirected to - Cannot access this site as problem with security certificate. I can access mail there if I click on 'continue to website - not recommended' & address bar turns pink. I have tried in 'Google Help' with mail & added recommended addresses to 'trusted site' but dosen't change the error.
Using IE 8 on MS Windows XP Help ME I am :confused

 

Sorry for rather long delay in thanking you for taking the time to answer my query Goldenskull. Not the problem though, unfortunately Still have it but was advised by a 'helpdesk' query through a magazine issue I subscribe to that.. [Quote...'It appears that Google may have neglected to renew their security certificate before it expired. When things all went runny, Google jumped to renew the certificate but as it had already expired, your browser, and many many more around the planet, were hesitant to accept a possibly hijacked security certificate. It doesn't appear to be a 'hack' - just an administrative oversight. Simply accepting the new certificate should be all that is needed, but as the new certificate is from a different signing authority, a lot of users have raised their eyebrows way off their faces in support of the hack paranoia. Fear not : Google just found a commercially better deal, and ran with it, in the face of looking silly. Or so it appears. You may need to clear out 'trusted site' status from your browser to allow a new certificate to be recorded against this site'.] I am still unable to fix this, even after cleaing my 'Trusted Sites' as advised