Unless those are pozidrive screws (I don't think they are), a pozidrive screwdriver will be more likely to strip the screws than the correct screwdriver, as the additional vanes will tend to hold it out of the screw rather than sitting in properly.

I don't think I'd agree with Roger's assessment to ever use the wrong screwdriver, but if it's already stripped, try anything. I'd still try the right size first. Of course, once you've got it out, you ought to replace the screw.