Socket error # 11001

[jannuh]

Hi,
- Since installing V7.21 this week I get an error reporting: Socket error # 11001 Host not found.
- Didn't change settings (pop3 SSL/TLS)
- Checked settings, look fine, as they were before.

Checked mail with Thunderbird pop3 (with and without SSL/TLS) and with Mailstore Home (Imap),
both programs mail is coming in fine.
Checked with ISP, they report no problems.

Any idea?