The cookie issue is a cookie/browser/security program issue, with too many variables on a persons computer that PPRuNe will never be able to account and fix them all.
However, until cookie handling is a non-issue worldwide and with every browser on earth, look forward to this coming up every once in awhile.
Things to suggest:
1. Delete cookies, then restart.
2. Make sure 'remember me' is always checked upon login.
3. Check your security softwares settings or turn it off for a second, and see if you still have a problem using PPRuNe.
4. Make sure you use pprune.org in your connections and not pprune.com.
5. Rub your head and pat your tummy.
Thanks Ridley!
