Here is the reason as to why it is blocked (at least as per the link provided):
Safe Browsing
Diagnostic page for
www.usacracing.com
What is the current listing status for
www.usacracing.com?
Site is listed as suspicious - visiting this web site may harm your computer.
Part of this site was listed for suspicious activity 2 time(s) over the past 90 days.
What happened when Google visited this site?
Of the 141 pages we tested on the site over the past 90 days, 67 page(s) resulted in malicious software being downloaded and installed without user consent. The last time Google visited this site was on 2010-09-02, and the last time suspicious content was found on this site was on 2010-09-02.
Malicious software is hosted on 1 domain(s), including kkiiy.com/.
This site was hosted on 1 network(s) including AS26078 (JRTHOMPSON).
Has this site acted as an intermediary resulting in further distribution of malware?
Over the past 90 days,
www.usacracing.com did not appear to function as an intermediary for the infection of any sites.
Has this site hosted malware?
No, this site has not hosted malicious software over the past 90 days.
How did this happen?
In some cases, third parties can add malicious code to legitimate sites, which would cause us to show the warning message.
Next steps:
* Return to the previous page.
* If you are the owner of this web site, you can request a review of your site using Google Webmaster Tools. More information about the review process is available in Google's Webmaster Help Center.