Can a private source see where I surf?

Am wondering if a private source / person can find out remotely what I do on the internet with my computer.
If so, how? and, if so, what can I do to prevent this?

Reason for asking: a psycho stalker who's bothered me for years is telling me with fair accuracy what I am doing on the web, i.e. sites visited, searches made, etc.
Just a stab in the dark and a good guess? Cripes, I'd hate for anyoneto be able to invade my privacy like that.
I am certain that my hotmail, yahoo, and netzero mailboxes have been compromised because content from them had been mailed back to me from the psycho - and my passwords are as strong as they can be.

Ideas please?

Thanks and Blessings,
Port-o-san

 

First thought, contact the police. Regardless of how they do it, stalking is not legal, digitally or otherwise, neither is breaking into your personal property.

Second, all the general methods to secure a network can be employed. Keep your computer up to date for security patches. Run anti-virus, and anti-spyware software. Use a good firewall. Change all your passwords, to new good passwords.

If this person has had physical access to your computer, or you just don't think you can get it clean, back up your data, format the computer, reload your software, restore your data, and then change all your passwords again.

 

Definitely go to the malware thread. If this person has access to your passwords etc then it seems likely that there is a keylogger involved (almost certainly software).

Do they/have they had physical access to your PC or is this all online? There are hardware devices that plug into your PC (into the PC with the keyboard plugged into them) that can also act as keyloggers but wouldn't show up as malware. Someone using one of those would need physical access to the PC to recover the data though (unless they've come a long way since I saw them).

Good Luck, contact the police if you need to. As suggested above this is easy enough to prove it's happening, may be harder to prove who is doing it though.

Oh, and don't shop online / do internet banking etc while there may be a keylogger on your PC. You don't want to give away your credit card details...

 

First, thanks to all for concern and advice.

Person has had zero physical contact with my computer - person is in a neighboring country, even, but has visited here and "camped out at my doorstep" by renting across the street twice - in different towns.
I think my computer is both clean and secure = even had a close pal who is a certified (and certifiable) IT come and look things over - he gave a clean bill of health.
All I can figure is that e mail accounts must have been hacked somehow, but that still doesn't explain knowing what websites this computer has visited.
This is all just a bit spooky, even though I have done nothing wrong.

I have saved the e mail letters she sent me, describing my internet use, her desire for me (UGH! She's 6'3" and 450#, looks like the horned helmet woman of opera lore!) and her belief that she and I are somehow "married". She has even called my home and my wife's work and said horrible things.
She's quite disturbed, on a ton of heavy drugs, and I think she could be dangerous to my welfare.
Police? HAHAHA! Yes, I went to my local police - the officer laughed - no, laughedin my face and said,"You're a big boy - handle this yourself!" Tried our sheriff's dept. same story. Contacted the state's attorney who told me that they would do nothing until a police report is filed.
God save you if you ever need your state to stick up for you in Florida!

 

As I'm from the UK I don't know much about your law enforcement, this may be a silly question but can the FBI not help? or have you considered trying them and if not are there other agencies even non law enforcement that can help you?