We report experimental evidence for bandwidth collapse occurring in links employing vertical cavity lasers under conventional launching conditions. Small launch misalignments are found to result in link bandwidths up to 40% below the modal bandwidth of the fibre with eye closure penalties of 4 dB. This effect can cause gigabit/s link lengths to be limited to less than previously thought. By implementing restricted mode launches using angled launch techniques we show that significant performance improvements are achievable. In particular, by adopting an angle of 8° between the launch axis and the fibre end face we show that the transmission bandwidth is 100% greater than the 550 MHz.km fibre bandwidth for a wide range of launch misalignments.