Unusual problem with ASA 5505

Hi,

I'm having this very unusual problem with ASA 5505.
ASA was configured almost two years ago. No problem till now (of course).
For some reason ASA is blocking one IP.
Should I mention that no change to config or internal network is done.
If I bypass ASA and plug-in directly in to ISP router no IP blocking.
This is from log (when I tried to use FTP):
7 Nov 04 2009 12:18:41 609002 97.74.144.146 Teardown local-host outside:97.74.144.146 duration 0:00:00

6 Nov 04 2009 12:18:41 302014 97.74.144.146 192.168.0.101 Teardown TCP connection 3411 for outside:97.74.144.146/21 to inside:192.168.0.101/1564 duration 0:00:00 bytes 0 TCP Reset-O

6 Nov 04 2009 12:18:41 302013 97.74.144.146 192.168.0.101 Built outbound TCP connection 3411 for outside:97.74.144.146/21 (97.74.144.146/21) to inside:192.168.0.101/1564 (75.250.20.50/2549)

7 Nov 04 2009 12:18:41 609001 97.74.144.146 Built local-host outside:97.74.144.146

I tried to ping, www ... nothing, result is the same, getting "Teardown TCP connection".

Any help would be highly appreciated.

Thanks.