Using five IVs at the same time in an ANOVA makes it a very complicated design. Depending on the number of levels each IV has, your number of groups may become very large, resulting in the error message you mention. Specifically, assuming that each IV is a between subject factor with two levels (the best case scenario), you would have 2x2x2x2x2 = 32 groups. Apperantly you have some IVs with more than two levels, making the number of your groups over 50.
In most cases, it is not necessary to run an ANOVA with some many factors. Are you sure you are using the appropriate analysis?