Hi
I really need your log files to be able to tell you what is really the problem, but allready from your posted stats I am getting an idea.
Just an example:
1847 21 May, 21:22:09 Storbritannien host213-120-115-68.in-addr.btopenworld.com 4 Windows XP Explorer 6.0
1828 21 May, 14:44:03 Storbritannien host213-120-115-68.in-addr.btopenworld.com 5 Windows XP Explorer 6.0
1825 21 May, 13:14:30 Storbritannien host213-120-115-68.in-addr.btopenworld.com 3 Windows XP Explorer 6.0
1819 21 May, 07:44:34 Storbritannien host213-120-115-68.in-addr.btopenworld.com 3 Windows XP Explorer 6.0
Are treated as 4 different unique visitors in your stats, but in reality they are the same guy.
and:
1812 21 May, 05:47:09 De Forenede Stater cache-rr02.proxy.aol.com 8 Windows XP AOL 9.0
1809 21 May, 05:45:55 De Forenede Stater cache-rr08.proxy.aol.com 4 Windows XP AOL 9.0
1810 21 May, 05:45:29 De Forenede Stater cache-rr04.proxy.aol.com 2 Windows XP AOL 9.0
1811 21 May, 05:30:58 De Forenede Stater cache-rh06.proxy.aol.com 1 Windows XP AOL 9.0
Are treated as 4 different visitors in your stats, but in reallity it is 1 unique visitor. AOL users use multiple IPs in the same session.