Broken pipe: core_output filter in apache log?

Hi,

I moved a word press mu site to virtualmin and I am getting this error message in the apache error log.

[info] [client x.x.x.x] (104)Connection reset by peer: core_output_filter: writing data to the network

[info] [client x.x.x.x] (32)Broken pipe: core_output_filter: writing data to the network

[info] [client x.x.x.x] (104)Connection reset by peer: core_output_filter: writing data to the network

[info] [client x.x.x.x] (32)Broken pipe: core_output_filter: writing data to the network

It appears to happen every time somebody visits the site.
The site itself works fine.
Any ideas?

Regards,

Keyvan