@LUAPWHO: I just Googled with "ios paypal" and the error message you're getting... the only possibly useful hit I found was in the Apple Support Communities forum... there's a thread with the subject "IOS5 Issue - Safari cannot open page because it could not establish a secure connection to the server". An explanation/solution posted in the thread is... "It appears that iOS5 increased its security protocols and, therefore, will not allow access to sites where there is a "redirect" to the secure site or where the SSL is not "perfect." I contacted the site that i was trying to access and they removed the redirect, tested the access and it worked. Bottom line, bad SSL certificates and redirects to secure sites won't work with iOS5."
This is over my head in terms of technospeak, so I dont know how right or useful this is.
Alternatively, a lower tech workaround that might work is to install the Paypal app from App Store (its an iPhone app, but works fine on iPad too).
Or, just try resetting the device to factory settings!
Hope this helps.