My site http://bankcd.com has been removed from the Google's search
results. They only indicate that I should review the Webmaster
Guidelines and let them know when I make the changes. Unfortunately I
don't know which guideline's I may have violated. Anybody can help?

PS. If you search for backlinks you may still see many old links from
petrix.com. These links have been removed and Google has been notified,
however they still reply with "We strongly encourage you to review
our Webmaster Guidelines".

It hasn't been removed - Google has ~10 pages from it indexed.

The bankcd.com home page (bankcd.com/index.html) has been removed.
There is no cache (search for cache:bankcd.com). Google customer
support keeps indicating, "We strongly encourage you to review our
Webmaster Guidelines".