This is an email I received from the Google Adwords Team about my account. Apparently it had been compromised and it is hard to tell what the problem was if I just was loging in normally.

Hello,

Thanks for your continued patience. Our AdWords Specialists have performed
a thorough investigation of your account , and I’ll detail
our findings and recommendations below.

WHAT WE FOUND

Our AdWords Specialists found that your account was compromised between 3
July 2010 – 7 July 2010 via login email ‘.’ The
following campaign show unauthorized changes: xxxx. No
unauthorized costs accrued in your AdWords account.

NEXT STEPS

1. Please delete the compromised ad and campaign and recreate your
original ads in a new campaign.

2. All your campaigns have been paused to allow you to make any necessary
changes. We also recommend reviewing and making any desired changes to
your account settings.

3. We strongly recommend removing any unwanted software in all of your
computers and changing your Google Account password. Be sure to clean your system first, and then change your password, as malware could capture your password if it’s still present within your computer. If we detect
unauthorized access again, your account will be suspended again.

4. Please confirm that you have completed a malware scan and changed the
password. We will then reactivate your account.

TIPS ON ACCOUNT SECURITY

You can protect yourself from unauthorized account access in the future by
following these tips:

I. Phishing Prevention

1. Don’t reply to, or click links within, emails that ask for personal,
financial, or account information.
2. Check the message headers. The ‘From:’ address and the ‘Return-path’
should reference the same source.
3. Instead of clicking the links in emails, go to the websites directly by
typing the web address into your browser, cut and paste, or use bookmarks.
4. If on a secure page, look for “https” at the beginning of the URL and
the padlock icon in the browser.
5. Use a browser that has a phishing filter (Chrome, Firefox, Internet
Explorer 7 or later, Safari, or Opera).
6. Use strong passwords. A strong password should be unique; include
letters, numbers, and symbols; and be changed regularly.
7. If you ever need to change your account information, such as your
billing details or your password, you should always sign in to your
account from the main AdWords login page (https://adwords.google.com) and
make the changes directly within your account. For more information on
changing your username and password, read our Help Center article at

II. Malware Prevention

1. Keep your computer’s antivirus and antispyware software, browser, and
security patches up to date.
2. Regularly run system scans.
3. Exercise caution whenever you’re prompted to download an email
attachment, follow an instant-message link, install a plug-in, or download
an unfamiliar piece of software. Remember that crimeware can be disguised
to resemble anti-virus software. Always research a company’s reputation
before downloading its software or visiting its website.

III. Unauthorized Login Prevention

1. Secure and encrypt your wireless network.
2. Don’t leave your computer unattended. If you’re using a public
terminal, make sure you log out of all your accounts before you leave.
3. Assign a separate login to each user. Don’t share logins and passwords.
4. Always grant the lowest access level necessary to each login email.

Please write us to confirm that you have completed a malware scan and
changed the password. We will be happy to then reactivate your account.

Sincerely,

Sudipta Chakraborty
The Google AdWords Team