Things stopped working since I've upgraded to V29

Question

There is something very wrong with FF on my laptop (now V30). I am writing this from my desktop, because one of the problems I'm having is that I can't log in, nor even start a new account from there.
The problem started when I updated to the version 29. The first thing I noticed was that the + sign you click to open another tab had disappeared. Ctrl+T didn't work every time either. So, I looked in help to see if I could find a solution. Seems I am not the only one with the problem The only "solution" I could find was to reset the default, which I would have preferred not to do, if I could avoid it.
Anyway, no one seems to have said that this solution has worked for them, so I thought I'd write my own comment. Seems one has to log in first. So, went to log in (I had the log in details saved in my password manager) It wouldn't accept it, (didn't say I had the wrong password, the page just kept refreshing and asking for the password again) so I asked to reset the password. The email didn't arrive. Asked again, several times, still didn't arrive.
It also said that if you're not yet registered, you can do so by asking a new question. So, thought I'd do that. No such luck, the register bit seems to be greyed out!!!
I got used to the +sign missing and stopped worrying about it. Then, I tried to log into you-tube and it wouldn't let me. Told me it had a problem that FF wasn't accepting cookies. Checked - it was. Then I followed their trouble shooting suggestions, including clearing the cache (which, as it happens I did the day before; didn’t help.
Then I started searching FF for solutions.
I gave up, and did the reset - didn't fix any of the problems, except the + sign for opening a new tab had reappeared.
Then I attempted to write here again and that's when I remembered the problem I came across when the problem started with the tabs. You can't write to Mozilla, unless you sign in, and it won't let me sign in!
It now seems to me that things I write on FF (like filling in online forms etc) don't register somehow. I have written people online emails, and never got an answer. I presumed they were rude, but now think they never got it!
I attempted to log into my Apple account yesterday and it insisted that my date of birth was incorrect!!! I logged in through IE, where it was happy with my date of birth.
Generally, I often have pages that won't open, keep getting errors, yet they will open in IE.
The cookie problem keeps coming up, for instance:
“The page isn't redirecting properly
Firefox has detected that the server is redirecting the request for this address in a way that will never complete. This problem can sometimes be caused by disabling or refusing to accept cookies.”
Since I reset it, spelling check no longer works in any page I use through FF. (It IS set to “check my spelling as I type” in options) FWIW, it does work in TB on the same computer. Another, more troubling thing started to happen. For instance, if I attempt to purchase something through Paypal, I got a warning about the site being unsafe. First time I happened, I was about to purchase something from as site I have never used before, so I actually believed the warning. I then attempted to log into PayPal by typing in the URL, still got the same warning. I then tried it from both IE on the same computer and FF on the desktop. Both worked fine. I even phoned PayPal to double check that all was OK. Edit… I have discovered that disabling Kaspersky Safe Money AddOn fixed that problem, yet it is also enabled on my desktop and it hasn’t created a problem here.
How do I fix all these problems? I have Windows 7 Pro on both computers - 64bit on the desktop and 32bit on the laptop
I reiterate, I am writing this from my desktop, which is not where the problem is, so I am presuming that the troubleshooting that is about to run will not be of much use

Answer 1

It could be the work of one of your add-ons, or even add / mal-ware.
Look thru your add-ons list and make sure you know what each one is
there for. Also, check the programs that are on your computer
'''Windows:''' Start > Control Panel > Uninstall Programs.
'''Mac:''' Open the "Applications" folder
'''Linux:'''
* [http://www.freesoftwaremagazine.com/articles/see_all_your_installed_applications_ubuntu_unity Ubuntu Unity]''' {web link}
* Xfce: Applications Menu category sections
* options depends on the package manager and the desktop environment
Go thru the list. If you find something that you don't
know what it is, use a web search.
'''''[https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-caused-malware Troubleshoot Firefox Issues Caused By Malware]''''' {web link}