Twitter Suspending Accounts

Most of October-December I was tweeting to approx 2500 tweet accounts, losing approx 10 a day due to twtter suspending them. to bad luck, and just generated replacements. This month so far Twitter have been suspending approx 500 accounts a day, I've tried changing everything I can and they are still pulling accounts as fast as I can create them. Does anybody have any ideas?

Were they created with unique IPs? Are you tweeting from proxies?

I use a rolling list of proxies when creating the accounts, but I have also bought some both are effected.

I tweet from approx 60 static ips, plus some proxies again rotating.