Common problems with chips happen in several areas:

• Interference Noise
• Deficient Models
• Circuit Architecture Issues

And, that's based on the premise that the simulated IC functions.

Please go to Help for IC Designers and read the material on:

• Simulation vs. Silicon
• Noise Reduction
• Foundry Model Problems

If that doesn't help with your situation, please contact us. Extensive experience in IC design and semiconductor models allows us to deal with many of the "not seen in simulation" issues. 

If you are an OEM or PCB designer with custom IC problems, consider technical oversight for these projects.  This generally results in:

• Cost Reduction For Final Product
• Lower NRE
• Faster Time to Market