TCassio,
I'm using IE6(sp2) without any problems. On RARE occasions a cookie or page in the cache will expire and IE won't catch it (Ive only had this happen twice in about six years). I'm not familar with Maxthon but clearing out the 'temporary internet folder' in IE might be worth a try. Also, if the date on your PC is really hosed, some cookies will expire unexpectedly.
Good luck.
Ken