Im receiving unsent emails from my hotmail account

It does sound suspicious.

Assuming you have anti-virus, and it's up-to-date do a full scan.  If not get a free one such as  Microsoft Security essentials or free.avg.com

download (and update) anti-malware -such as Malwarebytes or Spybot search & destroy

If possible do this from a different computer and disconnect your PC from the internet while you are running the anti-malware

You should also change your hotmail account, but best to do this from a different (clean rather than internet cafe) PC, in case there is a keylogger installed on your PC

For the emails that you have received on gmail.com from your hotmail.com account, could you provide us the email message headers (remove your gmail.com and hotmail.com email address and put dummy address instead). Procedure below

I believe those are the spoofed emails, not sent from the hotmail.com but they appears as if they were sent from hotmail.com. You should not be worried about them but make sure you do not open the attachment they are sending.

Message headers and how to extract them.

Headers contain tracking information for an individual email, detailing the path a message took as it crossed mail servers. Select your webmail provider or email client below for instructions on finding headers for a message.

http://mail.google.com/support/bin/answer.py?answer=22454

like stated above, it sounds like you have a virus on your computer and should run the suggested programs + combofix + ccleaner

I ran the scan and nothing was found. I have not received more emails like last two before.

If you receive any then check the email message headers as suggested above and post the logs. I believe they were spoofed messages.

The scanner had email option setup so maybe it was activated by mistake. I have not received more emails so this looks like the possible reason this could have happened.

Thanks