About messages in cache.log of squid

Issue

• Following 8 messages were output in cache.log of squid on our customer's system. Please answer the following questions about each message.

   1) Does this message influence on his system?
   2) If the answer of 1) is yes, what is the action that the customer should take 
      after this is output?
   3) If the answer of 1) is no, is there the method for not outputting it?

 [Message #1]
 2013/09/13 09:12:45| ipcacheParse: No Address records in response to 'ipv6.msftncsi.com'

 [Message #2]
 2013/09/12 12:22:18| clientReadRequest: FD 134 (172.16.7.191:62593) Invalid Request

 [Message #3]
 2013/09/12 15:06:56| sslReadClient: FD 50: read failure: (110) Connection timed out

 [Message #4]
 2013/09/12 18:21:41| sslWriteClient: FD 169: write failure: (32) Broken pipe.

 [Message #5]
 2013/09/12 18:59:03| httpReadReply: Excess data from "GET http://c.baidu.com/c.gif?t=0&q=%C8%FD%C9%FA%C8%FD%CA%C0
 %D5%ED%C9%CF%CA%E9%BC%C7+%CF%C2%BE%ED&p=0&pn=1"

 [Message #6]
 2013/09/12 10:04:03| parseHttpRequest: Requestheader contains NULL characters
 2013/09/12 10:04:03| Failed to parse request headers: http://dm.mlstat.com/update/dm/wg.php
 POST http://dm.mlstat.com/update/dm/wg.php HTTP/1.1
 Accept: */*
 Content-Type: application/x-www-form-urlencoded

 [Message #7]
 2013/09/12 08:34:09| ctx: enter level  0: 'http://gchart.yahoo.co.jp/h?s=998407.O'
 2013/09/12 08:34:09| WARNING: unparseable HTTP header field {HTTP/1.1 200 OK}
 2013/09/12 08:34:09| ctx: exit level  0
 2013/09/12 08:34:09| WARNING: unparseable HTTP header field {HTTP/1.1 200 OK}

 [Message #8]
 2013/09/12 12:02:44| ctx: enter level  0: 'http://vap3sna1.lijit.com/www/delivery/lg.php?bannerid=33990&campaigni
 d=232&cids=232&bids=33990&zoneid=211179&retarget_matches=null&tid=211179_e586bad4277144a5b1eee2253fc68763&channel
 _ids=,&fpr=f72008f3cce9494804544f1dcd707b4a&loc=http%3A%2F%2Fo.yieldsquare.com%2Fwww%2Fdelivery%2Fafr.php%3F14%3D
 1%26zoneid%3D27%26loc%3Dmatome.naver.jp%26id%3Dlfkgmnnajiljnolcgolmmgnecgldgeld%26v%3D0.17.7%26ord%3D1%26cb%3D32a
 24543d49b%26r%3D1&referer=http%3A%2F%2Fo.yieldsquare.com%2Fwww%2Fdelivery%2Fafr.php%3F14%3D1%26zoneid%3D27%26loc%
 3Dmatome.naver.jp%26id%3Dlfkgmnnajiljnolcgolmmgnecgldgeld%26v%3D0.17.7%26ord%3D1%26cb%3D32a24543d49b%26r%3D1&cb=8
 2975616'
 2013/09/12 12:02:44| WARNING: unparseable HTTP header field {: }
 2013/09/12 12:02:44| ctx: exit level  0
 2013/09/12 12:02:44| WARNING: unparseable HTTP header field {: }