Banned ip or what?

Hi everyone (and merry Christmas ^_^)...
here's my problem:

all my sites hosted on a DH machine (about 10) are unreacheable from my IP. My ISP use a Wide Area Network, and lot of users share the same IP.
I can access my sites using others IPS connections or using a proxy. The only case I cannot open my sites is using my connection directly (but I can open sites hosted on different DH machine).

The traceroute for one of my sites end here:

18 116 ms 117 ms 158 ms ae-2-52.bbr2.Washington1.Level3.net [4.68.121.33]
19 194 ms 194 ms 193 ms ae-0-0.bbr2.LosAngeles1.Level3.net [64.159.1.126]
20 194 ms 195 ms 194 ms 4.68.102.139
21 196 ms 194 ms 237 ms 4.78.195.170
22 * * * Richiesta scaduta. (TIMEOUT)

Tracert to other DH hosted sites (on different machine) are fine (as follow):

17 30 ms 30 ms 30 ms ae-0-52.mpls2.Milan1.Level3.net [213.242.64.18]
18 30 ms 30 ms 30 ms so-4-1-0.bbr2.Frankfurt1.Level3.net [4.68.128.185]
19 197 ms 197 ms 197 ms ae-0-0.bbr2.LosAngeles1.Level3.net [64.159.1.126]
20 198 ms 197 ms 197 ms 4.68.102.43
21 198 ms 198 ms 198 ms 4.78.195.170
22 201 ms 200 ms 200 ms basic-jolly.quid.dreamhost.com [205.196.223.121]

DH supports told me no block has been set... I really have not idea. Anybody ha a suggestion?

Thank :)