Program freezes

  while (codeCollection.Count < numberOfCodes)

        {       
            

            String currentCode = generateCode();

            CodeVerification cv = new CodeVerification();

           
            if ((cv.checkWords(currentCode) == -1) && (cv.checkSameChars(currentCode) == -1) && (cv.checkCodeMix(currentCode, percentLet, percentNum) == -1))
            

		{
                if (codeCollection.Add(currentCode))

                {
                    filePrint.WriteLine(currentCode);
                }
            }
            }