The request was rejected by the HTTP filter

ISA 2004 console > Configuration > Add-Ins > Web Filters tab > properties
of compression Filter > select Enable this filer. > Ok > Apply.

try way 2:

ISA2004 error 12217,Help me!!
取消驗證正則化
如果URL有高位字符請求，同樣要取消選框
把HTTP過濾器禁用了試試

詳情請見：
http://www.microsoft.com/china/technet/prodtechnol/isa/2004/plan/httpfiltering.mspx

Error Code: 500 Internal Server Error. The request was rejected by the HTTP Security filter. Contact your ISA Server administrator. (12217)

1. 打開ISA Server控制檯.

2. 展開ISA Server.

3. 點擊防火牆策略,選擇需要管理的策略.

4. 點擊右鍵, 點擊配置HTTP.

5. 取消阻止高位字符的選項，點擊確定.

6. 點擊應用更新策略，點擊確定.