Graphite skin and IE8

[sgiudice]

There are any troubles with the skin "Graphite" in internet explorer 8 (firefox works fine); in showcase project, if I choose the ListGrid "Row numbering" and then I move over with mouse on the grid I get this warning in my console:

[WARN] 404 - GET /images/ListGrid/row_Over.png (127.0.0.1) 1414 bytes
   Request headers
      Accept: */*
      Referer: http://127.0.0.1:8888/Showcase.html?gwt.codesvr=127.0.0.1:9997
      Accept-Language: it
      User-Agent: Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0; .NET CLR 1.1.4322; .NET CLR 2.0.50727; InfoPath.2; .NET CLR 3.0.04506.648; .NET CLR 3.5.21022; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729)
      Accept-Encoding: gzip, deflate
      Host: 127.0.0.1:8888
      Connection: Keep-Alive
      Cookie: GLog=%7B%0D%20%20%20%20left%3A177%2C%20%0D%20%20%20%20top%3A240%2C%20%0D%20%20%20%20width%3A640%2C%20%0D%20%20%20%20height%3A580%2C%20%0D%20%20%20%20priorityDefaults%3A%7B%0D%20%20%20%20%20%20%20%20Log%3A4%0D%20%20%20%20%7D%2C%20%0D%20%20%20%20defaultPriority%3A3%0D%7D; JSESSIONID=vfdu4ny0kclh; skin_name=Graphite
   Response headers
      Content-Type: text/html; charset=iso-8859-1
      Content-Length: 1414

My configuration:
•Development mode
•SmartGWT 2.2
•GWT 2.0.3
•Internet Explorer 8
•Windows XP SP3

thanks in advance
sg