There's some funny thing with graphs that (should) show up, when comparing teams.
In some cases, the just don't show up (showing 'red cross' instead)
However this does not happen in all cases and seems to be dependent on team selection for comparison.

[url=http://www.boincstats.com/stats/compare_graph.php?pr=bo&table=teams&id%5B%5D=Poland&id%5B%5D=SETI@Home+Poland&id%5B%5D=POLAND+-+SetiTeam+2000&id%5B%5D=Boinc+InfoPC+%26+BARWKOMP' target='_blank]URL1[/url]
[url=http://www.boincstats.com/stats/compare_graph.php?pr=bo&table=teams&id%5B%5D=Boinc+InfoPC+%26+BARWKOMP&id%5B%5D=TuningPC&id%5B%5D=BOINC@Poland&id%5B%5D=DistributedComputing@P%26%23322%3Bock&id%5B%5D=Poland+-+Cracow+Sharks' target='_blank]URL2[/url]
[url=http://www.boincstats.com/stats/compare_graph.php?pr=bo&table=teams&id%5B%5D=SETI@Home+Poland&id%5B%5D=TuningPC&id%5B%5D=boinc.pl&id%5B%5D=SETI@Gorzow+Wlkp&id%5B%5D=BOINC@Poland' target='_blank]URL3 (this one works)[/url]

Can you add a link to the page where you select the teams, and which teams are selected?

[url=http://www.boincstats.com/stats/boinc_team_stats.php?pr=bo&st=0&to=100&or=&co=Poland' target='_blank]Here goes (Polish teams)[/url]
Select 1,2,3,4,5 to get an error.
Select 1,2,3 and 5,6 to get good one.
These examples, there are more combinations, also on lower positions, so this doesn't seem to be a one team problem.

Agreed, a bug has been sighted. I'll fix it.

Problem solved.

Team 4 of the list had a '&' in its name, that was causing problems in the URL. As I recently introduced unique id's for all the BOINC teams, I'm now also using that ID for the compare graph instead of the name.

Good work. So now it is 'nameproof'